waveguides with mode-degeneracy optical gyroscopes

合集下载

超材料翻译

Naturematerials LETTERSPublished online : 18 APRIL 2010| DOI:10.1038/NMAT2747A single-layer wide-angle negative-index metamaterial at visible frequencies在可见光频率的一种单层广角负折射率超材料Metamaterials are materials with artificial electromagnetic properties defined by their sub-wavelength structure rather than their chemical composition.基于亚波长结构而非化学结构，超材料也叫人工电磁材料。

Negative-index materials(NIMs) are a special class of metamaterials characterized by an effective negative index that give rise to such unusual wave behavior as backwards phase propagation and negative refraction.负折射率材料（NIMs）是一类具有有效负折射率的特殊超材料，能够产生逆向传播和负折射的不同寻常的波行为。

These extraordinary properties lead to many interesting functions such as sub-diffraction imaging and invisibility cloaking.这些非凡的性能使得有有趣的功能，如子衍射成像和隐蔽伪装So far ,NIMs have been realized through layering of resonant structures,such as spilt-ring resonators ,and have been demonstrated at microwave to infrared frequencies over a narrow range of angles-of-incidence and polarization.到目前，负折射率材料（NIMs）已经通过谐振结构层实现，例如开环谐振器，而且在较窄范围的红外频率内的入射角和偏振也可以证明。

Pedestal antiresonant reflecting waveguides for robust coupling to microsphere resonators

January1,2000/Vol.25,No.1/OPTICS LETTERS73 Pedestal antiresonant reflecting waveguides forrobust coupling to microsphereresonators and for microphotonic circuitsB.E.Little,ine,D.R.Lim,and H.A.HausResearch Laboratory of Electronics,Department of Electrical Engineering and Computer Sciences,Massachusetts Institute of Technology,Cambridge,Massachusetts02139L.C.KimerlingDepartment of Material Sciences,Massachusetts Institute of Technology,Cambridge,Massachusetts02139S.T.ChuNational Institute of Standards and Technology,Gaithersburg,Maryland20899Received September10,1999Strip-line pedestal antiresonant ref lecting waveguides are high-confinement,silica integrated opticalwaveguides in which the optical modes are completely isolated from the substrate by thin high-index layers.These waveguides are particularly well suited for whispering-gallery mode excitation in high-Q microspheres.They can also be used in microphotonic circuits,such as for microring resonators.The theory and design ofthese structures are highlighted.Experiments that show high coupling efficiency to microspheres are alsodemonstrated. 2000Optical Society of AmericaOCIS codes:230.7370,230.5750,130.2790.Silica-based microsphere resonators1support whispering-gallery modes that exhibit Q values in excess of1010.Harnessing these huge Q values may enable microspheres to find potential for unprece-dented performance in applications calling for ultra-narrow linewidths,long energy decay times,large energy densities,or fine sensing of environmental changes.It is also of practical and commercial sig-nificance that these spheres are compact(they have submillimeter diameters),simple to fabricate,and inexpensive.Controlling the excitation and external Q’s of the whispering-gallery modes is vital to device performance.Although bulk1and discrete2–5optical components have been used to couple energy efficiently into microspheres,more widespread deployment of microspheres in practical devices will call for their integration with robust planar waveguide technology. Doing this represents an interesting challenge for conventional waveguides.That is,high-Q micro-spheres are composed of high-purity silica,a material whose low refractive-index value is commonly used for the cladding of planar waveguides.As a result, a silica sphere coupled to a conventional surface waveguide will lose most of its energy to substrate and cladding radiation.This loss may spoil the Q and reduce the device efficiency.Q spoiling could be alleviated if the waveguide cladding index were made significantly lower than that of silica.Unfortunately, such low-index materials are not readily available.In this Letter we demonstrate numerically and experi-mentally how simple silica-based strip-line pedestals, antiresonant ref lecting waveguides6,(ARROW’s),or SP ARROW’s for short here,can be used as a robust and efficient integrated-optics means to excite microsphere modes.We also show how these waveguides might find applicability in microphotonic circuits.Numerous methods have been developed for the excitation of whispering-gallery modes in microsphere resonators,as depicted in Fig.1.The devices used include the prism coupler,1the tapered fiber coupler,2,3 the polished half-block coupler,4and,more recently, the hybrid fiber–prism coupler.5The prism coupler is efficient and tunable,but it uses bulk components and is therefore less desirable for applications that call for robustness.It also lacks guided-wave control. The tapered fiber coupler is efficient and uses guided modes as the input–output waves,but it requires delicately drawn fibers less than5m m in diameter suspended in air.The polished half-block coupler offers a more robust coupling platform but yieldslow Fig.1.Methods for exciting whispering-gallery modes of high-Q microspheres.0146-9592/00/010073-03$15.00/0 2000Optical Society of America74OPTICS LETTERS/Vol.25,No.1/January1,2000 efficiencies because,as was mentioned above,energyin the sphere couples to the cladding radiation modes of the half-block.The hybrid fiber–prism makes useof the efficiency of the bulk prism,with the versatilityof optical fibers.The SP ARROW,depicted in Fig.2, overcomes the limitations of the foregoing couplers by providing mode isolation from the substrate,guided mode control,and a robust integrated optics platform.A cross-sectional view of the SP ARROW is shown schematically in Fig.2(a).Lateral mode confinementis achieved by deep etching;vertical confinement is accomplished by means of high ref lection.High re-f lection is produced by an alternating series of high-and low-index layers.In analogy with quarter-wave stacks,the thicknesses of the layers correspond to a quarter of the vertically directed guide wavelength(ex-plained below).The optimum thickness of the SP ARROW cladding layers(d L and d H)for low-leakage loss can be calcu-lated with good accuracy by a simple effective-index method and can be followed by numerical refinement,ifso desired.It is assumed that the high-and low-index values n L and n H,respectively,are given and that the waveguide core thicknesses W and d are selected to give a certain effective index.Only TE modes will be considered here,because TM ARROW modes are gener-ally much lossier.6The procedure to calculate d L andd H is as follows:First we compute the TM-polarized effective index of an air-clad slab waveguide of thick-ness W and core index n L.The effective index value so computed is labeled N L here.Next we choose a thick-ness d for the waveguide core layer.The optical fieldof a SP ARROW goes to zero at some point in the first thin high-index layer,near the core–high-index layer boundary.The vertical cladding layers of the SP AR-ROW can then be replaced by a mirror plane(in the ideal case).A conventional mode with this property is the second-order mode of a symmetric slab waveguide with thickness2d.That is,the second-order mode has a null in the center of the waveguide,a distanced from the core–clad interface,similar to our SP AR-ROW.Thus we compute the effective index for the TE-polarized second-order mode of an air–clad slab of thickness2d and core index N L.This effective index, which we label here N eff,is the approximate real partof the exact SP ARROW effective mode index.The op-timum thicknesses of the low-and high-index cladding layer(s)ared L෇14l0pN L22N eff2,dH෇14l0pn H22N eff2,(1)respectively,which are a quarter of the vertically directed guide wavelength,and where l0is the desired operating wavelength.Note that we use n H in the expression for d H,rather than some effective index N H in analogy with N L for d L,because n H and N H turn out to be almost identical.These starting values for d L and d H can be refined by use of a numerical mode solver,7if so desired.In the refinement process the numerically computed value of the effective mode index is substituted for N eff in Eqs.(1),and the refinement process is repeated.For example,consider a SiO2Si-based SP ARROW with the geometry shown in Fig.2(a)and with the parameters n L෇1.45,n H෇3.5,d෇2.0m m,l0෇1.55m m,and W෇6.0m m.In the approximate method one obtains N L෇1.4446, N eff෇1.4026,and thus d L෇1.12m m and d H෇120nm,from Eqs.(1).An exact numerical solution to this structure yields an effective index of1.4025 (in excellent agreement with the approximate method) and a leakage loss of less than0.5dB͞cm.Figure2(b) shows the field profile of the SP ARROW mode.Note that the optical field is almost entirely contained within the top core layer and is isolated from the substrate.A SiO2Si-based SP ARROW similar to that depicted in Fig.2(a)was fabricated in the Microsystems Tech-nology Laboratory at the Massachusetts Institute of Technology.In this device the substrate was silicon, and therefore there was only one high-index and one low-index cladding layer.The ARROW stack was fab-ricated upon10.16-V cm silicon wafers,with the ini-tial step being a thermal oxidation process to grow 1.6-m m-thick silica.This oxidation was followed by the deposition of120nm of amorphous silicon by low-pressure chemical-vapor deposition,which was in turn followed by the deposition of1.7m m of low-temperature oxide by plasma-enhanced chemical-vapor deposition. The ARROW stack was then patterned,and the low-temperature oxide was wet etched in a buffered oxide etcher.The remainder of the stack was then etched by reactive ion etching to form the SP ARROW waveguides. The waveguide width was designed to be8m m,but as a result of the etching process the top core layer eroded to approximately6m m.The wafer was diced and the facets of the waveguide samples were polished before they were used to couple light into the microspheres.A silica microsphere250m m in diameter was fabri-cated and coupled to the SP ARROW by direct contact. Figure3shows the transmission spectrum near a wavelength of1.55m m.Resonant dips are observed as the microsphere extracts power from the waveguide. These preliminary results show greater than85% extraction efficiency.The transmitted power levels in the absence of the sphere remain within approxi-mately5%of the peak values observed in Fig.3. The calculated effective index of the fundamental whispering-gallery mode is approximately 1.43,8 whereas that of the SPARROW is1.4025.We thereforeFig.2.(a)Cross-sectional geometry of a SP ARROW. Hatched regions,thin high-index layers.(b)Numerically simulated fundamental mode field,showing complete isolation from the substrate.January 1,2000/Vol.25,No.1/OPTICS LETTERS75Fig.3.Waveguide transmission response of a microsphere coupled to a SP ARROW.The center wavelength is close to 1.55mm.Fig.4.Calculated net loss (bending plus ARROW leakage)per round trip in a microring resonator SP ARROW.believe that this SP ARROW is exciting higher-order ra-dial (or deeper)whispering-gallery modes.Different device dimensions and (or)different refractive-index values for the low-index core can be used to phase match most microsphere modes,including the funda-mental.Because dust and moisture on the surface of the sphere are thought to be responsible for the degra-dation of the Q values over time,it may be beneficial to excite deeper radial whispering-gallery modes,which interact less with the sphere surface.In addition to serving as robust couplers for micro-sphere resonators,SP ARROW’s might find application as a technology for microphotonic resonator circuits.For instance,because of the air cladding and substrate isolation,these high-confinement waveguides can be bent into low-loss microring resonators.Unlike the conventional high-index waveguides used for micro-rings,9these devices make use of low-index silica,which may have better matching properties for op-tical fibers.Further,compared with compound-glass microrings,10SP ARROW’s use two more widely avail-able materials and do not directly rely on core–substrate index contrast to achieve low bending loss.As an example,net loss as a function of ring radius wascalculated numerically for the SP ARROW of Fig.2(a)with parameters n L ෇1.45,n H ෇3.5,d ෇2.5um,l 0෇1.55m m,W ෇3.0m m,d L ෇1.37um,and d H ෇120nm.Figure 4shows the bending-induced loss in decibels per resonator round trip.Note that bending loss exceeds ARROW leakage loss (dashed line)only when the radius becomes smaller than approximately 8m m.In practice,because of the low leakage loss,SP ARROW rings will be limited only by etch-induced surface roughness.In conclusion,strip-line pedestal antiresonant re-f lecting waveguides are low-index,high-confinement waveguides that achieve vertical confinement and sub-strate isolation by means of a few thin,high-index layers.They are ideally suited as robust couplers for microsphere whispering-gallery mode excitation and can phase match deep radial modes.SiO 2Si-based SP ARROW’s were fabricated and showed whispering-gallery mode excitation of approximately 85%.(As this manuscript went to press,we observed Q values of the order of 108and single-coupler efficiencies of approximately 98%.)High-confinement SP ARROW’s can also be bent into microring resonators with neg-ligible loss for radii as small as 10m m.They might therefore serve in microphotonic circuits.This research was supported in part by a Charles Stark Draper Laboratories research grant. D.R.Lim was supported in part by HIDE U.S.Army Research Office grant DAAG55-97-1-0366. B.E.Little’s e-mail address is belittle@.References1.M.L.Gorodetsky,A.A.Savchenkov,and V.S.Ilchenko,Opt.Lett.21,453(1996).2.J.C.Knight,G.Cheung,F.Jacques,and T.A.Birks,Opt.Lett.22,1129(1997).ine, B. E.Little,and H. A.Haus,‘‘Etched-eroded coupler for whispering-gallery-mode excitation in high-Q silica microspheres,’’IEEE Photon.Technol.Lett.(to be published).4.N.Dubreuil,J. C.Knight, D.K.Leventhal,V.Sandoghar,J.Hare,and V.Lefevre,Opt.Lett.20,813(1995).5.V.S.Ilchenko,X.S.Yao,and L.Maleki,Opt.Lett.24,723(1999).6.M.A.Duguay,Y.Kokubun,T.L.Koch,and L.Pfeiffer,Appl.Phys.Lett.49,13(1986).7.Optical Waveguide Mode Solver Suite ,Apollo Photonics,Inc.,Kitchener,Ont.,Canada.8.B.E.Little,ine,and H.A.Haus,J.Lightwave Technol.17,704(1999).9.B.E.Little,J.S.Foresi,G.Steinmeyer,E.R.Thoen,S.T.Chu,H.A.Haus,E.P.Ippen,L.C.Kimerling,and W.Greene,IEEE J.Photon.Technol.Lett.10,549(1998).10.B.E.Little,S.T.Chu,W.Pan,D.Ripin,T.Kaneko,Y.Kokubun,and E.Ippen,IEEE Photon.Technol.Lett.11,215(1999).。

物理学专业英语

华中师范大学物理学院物理学专业英语仅供内部学习参考！2014一、课程的任务和教学目的通过学习《物理学专业英语》，学生将掌握物理学领域使用频率较高的专业词汇和表达方法，进而具备基本的阅读理解物理学专业文献的能力。

通过分析《物理学专业英语》课程教材中的范文，学生还将从英语角度理解物理学中个学科的研究内容和主要思想，提高学生的专业英语能力和了解物理学研究前沿的能力。

培养专业英语阅读能力，了解科技英语的特点，提高专业外语的阅读质量和阅读速度；掌握一定量的本专业英文词汇，基本达到能够独立完成一般性本专业外文资料的阅读；达到一定的笔译水平。

要求译文通顺、准确和专业化。

二、课程内容课程内容包括以下章节：物理学、经典力学、热力学、电磁学、光学、原子物理、统计力学、量子力学和狭义相对论三、基本要求1.充分利用课内时间保证充足的阅读量（约1200~1500词/学时），要求正确理解原文。

2.泛读适量课外相关英文读物，要求基本理解原文主要内容。

3.掌握基本专业词汇（不少于200词）。

4.应具有流利阅读、翻译及赏析专业英语文献，并能简单地进行写作的能力。

四、参考书目录1 Physics 物理学 (1)Introduction to physics (1)Classical and modern physics (2)Research fields (4)V ocabulary (7)2 Classical mechanics 经典力学 (10)Introduction (10)Description of classical mechanics (10)Momentum and collisions (14)Angular momentum (15)V ocabulary (16)3 Thermodynamics 热力学 (18)Introduction (18)Laws of thermodynamics (21)System models (22)Thermodynamic processes (27)Scope of thermodynamics (29)V ocabulary (30)4 Electromagnetism 电磁学 (33)Introduction (33)Electrostatics (33)Magnetostatics (35)Electromagnetic induction (40)V ocabulary (43)5 Optics 光学 (45)Introduction (45)Geometrical optics (45)Physical optics (47)Polarization (50)V ocabulary (51)6 Atomic physics 原子物理 (52)Introduction (52)Electronic configuration (52)Excitation and ionization (56)V ocabulary (59)7 Statistical mechanics 统计力学 (60)Overview (60)Fundamentals (60)Statistical ensembles (63)V ocabulary (65)8 Quantum mechanics 量子力学 (67)Introduction (67)Mathematical formulations (68)Quantization (71)Wave-particle duality (72)Quantum entanglement (75)V ocabulary (77)9 Special relativity 狭义相对论 (79)Introduction (79)Relativity of simultaneity (80)Lorentz transformations (80)Time dilation and length contraction (81)Mass-energy equivalence (82)Relativistic energy-momentum relation (86)V ocabulary (89)正文标记说明：蓝色Arial字体（例如energy）：已知的专业词汇蓝色Arial字体加下划线（例如electromagnetism）：新学的专业词汇黑色Times New Roman字体加下划线（例如postulate）：新学的普通词汇1 Physics 物理学1 Physics 物理学Introduction to physicsPhysics is a part of natural philosophy and a natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy. Over the last two millennia, physics was a part of natural philosophy along with chemistry, certain branches of mathematics, and biology, but during the Scientific Revolution in the 17th century, the natural sciences emerged as unique research programs in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry,and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms of other sciences, while opening new avenues of research in areas such as mathematics and philosophy.Physics also makes significant contributions through advances in new technologies that arise from theoretical breakthroughs. For example, advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products which have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.Core theoriesThough physics deals with a wide variety of systems, certain theories are used by all physicists. Each of these theories were experimentally tested numerous times and found correct as an approximation of nature (within a certain domain of validity).For instance, the theory of classical mechanics accurately describes the motion of objects, provided they are much larger than atoms and moving at much less than the speed of light. These theories continue to be areas of active research, and a remarkable aspect of classical mechanics known as chaos was discovered in the 20th century, three centuries after the original formulation of classical mechanics by Isaac Newton (1642–1727) 【艾萨克·牛顿】.University PhysicsThese central theories are important tools for research into more specialized topics, and any physicist, regardless of his or her specialization, is expected to be literate in them. These include classical mechanics, quantum mechanics, thermodynamics and statistical mechanics, electromagnetism, and special relativity.Classical and modern physicsClassical mechanicsClassical physics includes the traditional branches and topics that were recognized and well-developed before the beginning of the 20th century—classical mechanics, acoustics, optics, thermodynamics, and electromagnetism.Classical mechanics is concerned with bodies acted on by forces and bodies in motion and may be divided into statics (study of the forces on a body or bodies at rest), kinematics (study of motion without regard to its causes), and dynamics (study of motion and the forces that affect it); mechanics may also be divided into solid mechanics and fluid mechanics (known together as continuum mechanics), the latter including such branches as hydrostatics, hydrodynamics, aerodynamics, and pneumatics.Acoustics is the study of how sound is produced, controlled, transmitted and received. Important modern branches of acoustics include ultrasonics, the study of sound waves of very high frequency beyond the range of human hearing; bioacoustics the physics of animal calls and hearing, and electroacoustics, the manipulation of audible sound waves using electronics.Optics, the study of light, is concerned not only with visible light but also with infrared and ultraviolet radiation, which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light.Heat is a form of energy, the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy.Electricity and magnetism have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an electric current gives rise to a magnetic field and a changing magnetic field induces an electric current. Electrostatics deals with electric charges at rest, electrodynamics with moving charges, and magnetostatics with magnetic poles at rest.Modern PhysicsClassical physics is generally concerned with matter and energy on the normal scale of1 Physics 物理学observation, while much of modern physics is concerned with the behavior of matter and energy under extreme conditions or on the very large or very small scale.For example, atomic and nuclear physics studies matter on the smallest scale at which chemical elements can be identified.The physics of elementary particles is on an even smaller scale, as it is concerned with the most basic units of matter; this branch of physics is also known as high-energy physics because of the extremely high energies necessary to produce many types of particles in large particle accelerators. On this scale, ordinary, commonsense notions of space, time, matter, and energy are no longer valid.The two chief theories of modern physics present a different picture of the concepts of space, time, and matter from that presented by classical physics.Quantum theory is concerned with the discrete, rather than continuous, nature of many phenomena at the atomic and subatomic level, and with the complementary aspects of particles and waves in the description of such phenomena.The theory of relativity is concerned with the description of phenomena that take place in a frame of reference that is in motion with respect to an observer; the special theory of relativity is concerned with relative uniform motion in a straight line and the general theory of relativity with accelerated motion and its connection with gravitation.Both quantum theory and the theory of relativity find applications in all areas of modern physics.Difference between classical and modern physicsWhile physics aims to discover universal laws, its theories lie in explicit domains of applicability. Loosely speaking, the laws of classical physics accurately describe systems whose important length scales are greater than the atomic scale and whose motions are much slower than the speed of light. Outside of this domain, observations do not match their predictions.Albert Einstein【阿尔伯特·爱因斯坦】contributed the framework of special relativity, which replaced notions of absolute time and space with space-time and allowed an accurate description of systems whose components have speeds approaching the speed of light.Max Planck【普朗克】, Erwin Schrödinger【薛定谔】, and others introduced quantum mechanics, a probabilistic notion of particles and interactions that allowed an accurate description of atomic and subatomic scales.Later, quantum field theory unified quantum mechanics and special relativity.General relativity allowed for a dynamical, curved space-time, with which highly massiveUniversity Physicssystems and the large-scale structure of the universe can be well-described. General relativity has not yet been unified with the other fundamental descriptions; several candidate theories of quantum gravity are being developed.Research fieldsContemporary research in physics can be broadly divided into condensed matter physics; atomic, molecular, and optical physics; particle physics; astrophysics; geophysics and biophysics. Some physics departments also support research in Physics education.Since the 20th century, the individual fields of physics have become increasingly specialized, and today most physicists work in a single field for their entire careers. "Universalists" such as Albert Einstein (1879–1955) and Lev Landau (1908–1968)【列夫·朗道】, who worked in multiple fields of physics, are now very rare.Condensed matter physicsCondensed matter physics is the field of physics that deals with the macroscopic physical properties of matter. In particular, it is concerned with the "condensed" phases that appear whenever the number of particles in a system is extremely large and the interactions between them are strong.The most familiar examples of condensed phases are solids and liquids, which arise from the bonding by way of the electromagnetic force between atoms. More exotic condensed phases include the super-fluid and the Bose–Einstein condensate found in certain atomic systems at very low temperature, the superconducting phase exhibited by conduction electrons in certain materials,and the ferromagnetic and antiferromagnetic phases of spins on atomic lattices.Condensed matter physics is by far the largest field of contemporary physics.Historically, condensed matter physics grew out of solid-state physics, which is now considered one of its main subfields. The term condensed matter physics was apparently coined by Philip Anderson when he renamed his research group—previously solid-state theory—in 1967. In 1978, the Division of Solid State Physics of the American Physical Society was renamed as the Division of Condensed Matter Physics.Condensed matter physics has a large overlap with chemistry, materials science, nanotechnology and engineering.Atomic, molecular and optical physicsAtomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions on the scale of single atoms and molecules.1 Physics 物理学The three areas are grouped together because of their interrelationships, the similarity of methods used, and the commonality of the energy scales that are relevant. All three areas include both classical, semi-classical and quantum treatments; they can treat their subject from a microscopic view (in contrast to a macroscopic view).Atomic physics studies the electron shells of atoms. Current research focuses on activities in quantum control, cooling and trapping of atoms and ions, low-temperature collision dynamics and the effects of electron correlation on structure and dynamics. Atomic physics is influenced by the nucleus (see, e.g., hyperfine splitting), but intra-nuclear phenomena such as fission and fusion are considered part of high-energy physics.Molecular physics focuses on multi-atomic structures and their internal and external interactions with matter and light.Optical physics is distinct from optics in that it tends to focus not on the control of classical light fields by macroscopic objects, but on the fundamental properties of optical fields and their interactions with matter in the microscopic realm.High-energy physics (particle physics) and nuclear physicsParticle physics is the study of the elementary constituents of matter and energy, and the interactions between them.In addition, particle physicists design and develop the high energy accelerators,detectors, and computer programs necessary for this research. The field is also called "high-energy physics" because many elementary particles do not occur naturally, but are created only during high-energy collisions of other particles.Currently, the interactions of elementary particles and fields are described by the Standard Model.●The model accounts for the 12 known particles of matter (quarks and leptons) thatinteract via the strong, weak, and electromagnetic fundamental forces.●Dynamics are described in terms of matter particles exchanging gauge bosons (gluons,W and Z bosons, and photons, respectively).●The Standard Model also predicts a particle known as the Higgs boson. In July 2012CERN, the European laboratory for particle physics, announced the detection of a particle consistent with the Higgs boson.Nuclear Physics is the field of physics that studies the constituents and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those in nuclear medicine and magnetic resonance imaging, ion implantation in materials engineering, and radiocarbon dating in geology and archaeology.University PhysicsAstrophysics and Physical CosmologyAstrophysics and astronomy are the application of the theories and methods of physics to the study of stellar structure, stellar evolution, the origin of the solar system, and related problems of cosmology. Because astrophysics is a broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.The discovery by Karl Jansky in 1931 that radio signals were emitted by celestial bodies initiated the science of radio astronomy. Most recently, the frontiers of astronomy have been expanded by space exploration. Perturbations and interference from the earth's atmosphere make space-based observations necessary for infrared, ultraviolet, gamma-ray, and X-ray astronomy.Physical cosmology is the study of the formation and evolution of the universe on its largest scales. Albert Einstein's theory of relativity plays a central role in all modern cosmological theories. In the early 20th century, Hubble's discovery that the universe was expanding, as shown by the Hubble diagram, prompted rival explanations known as the steady state universe and the Big Bang.The Big Bang was confirmed by the success of Big Bang nucleo-synthesis and the discovery of the cosmic microwave background in 1964. The Big Bang model rests on two theoretical pillars: Albert Einstein's general relativity and the cosmological principle (On a sufficiently large scale, the properties of the Universe are the same for all observers). Cosmologists have recently established the ΛCDM model (the standard model of Big Bang cosmology) of the evolution of the universe, which includes cosmic inflation, dark energy and dark matter.Current research frontiersIn condensed matter physics, an important unsolved theoretical problem is that of high-temperature superconductivity. Many condensed matter experiments are aiming to fabricate workable spintronics and quantum computers.In particle physics, the first pieces of experimental evidence for physics beyond the Standard Model have begun to appear. Foremost among these are indications that neutrinos have non-zero mass. These experimental results appear to have solved the long-standing solar neutrino problem, and the physics of massive neutrinos remains an area of active theoretical and experimental research. Particle accelerators have begun probing energy scales in the TeV range, in which experimentalists are hoping to find evidence for the super-symmetric particles, after discovery of the Higgs boson.Theoretical attempts to unify quantum mechanics and general relativity into a single theory1 Physics 物理学of quantum gravity, a program ongoing for over half a century, have not yet been decisively resolved. The current leading candidates are M-theory, superstring theory and loop quantum gravity.Many astronomical and cosmological phenomena have yet to be satisfactorily explained, including the existence of ultra-high energy cosmic rays, the baryon asymmetry, the acceleration of the universe and the anomalous rotation rates of galaxies.Although much progress has been made in high-energy, quantum, and astronomical physics, many everyday phenomena involving complexity, chaos, or turbulence are still poorly understood. Complex problems that seem like they could be solved by a clever application of dynamics and mechanics remain unsolved; examples include the formation of sand-piles, nodes in trickling water, the shape of water droplets, mechanisms of surface tension catastrophes, and self-sorting in shaken heterogeneous collections.These complex phenomena have received growing attention since the 1970s for several reasons, including the availability of modern mathematical methods and computers, which enabled complex systems to be modeled in new ways. Complex physics has become part of increasingly interdisciplinary research, as exemplified by the study of turbulence in aerodynamics and the observation of pattern formation in biological systems.Vocabulary★natural science 自然科学academic disciplines 学科astronomy 天文学in their own right 凭他们本身的实力intersects相交，交叉interdisciplinary交叉学科的，跨学科的★quantum 量子的theoretical breakthroughs 理论突破★electromagnetism 电磁学dramatically显著地★thermodynamics热力学★calculus微积分validity★classical mechanics 经典力学chaos 混沌literate 学者★quantum mechanics量子力学★thermodynamics and statistical mechanics热力学与统计物理★special relativity狭义相对论is concerned with 关注，讨论，考虑acoustics 声学★optics 光学statics静力学at rest 静息kinematics运动学★dynamics动力学ultrasonics超声学manipulation 操作，处理，使用University Physicsinfrared红外ultraviolet紫外radiation辐射reflection 反射refraction 折射★interference 干涉★diffraction 衍射dispersion散射★polarization 极化，偏振internal energy 内能Electricity电性Magnetism 磁性intimate 亲密的induces 诱导，感应scale尺度★elementary particles基本粒子★high-energy physics 高能物理particle accelerators 粒子加速器valid 有效的，正当的★discrete离散的continuous 连续的complementary 互补的★frame of reference 参照系★the special theory of relativity 狭义相对论★general theory of relativity 广义相对论gravitation 重力，万有引力explicit 详细的，清楚的★quantum field theory 量子场论★condensed matter physics凝聚态物理astrophysics天体物理geophysics地球物理Universalist博学多才者★Macroscopic宏观Exotic奇异的★Superconducting 超导Ferromagnetic铁磁质Antiferromagnetic 反铁磁质★Spin自旋Lattice 晶格，点阵，网格★Society社会，学会★microscopic微观的hyperfine splitting超精细分裂fission分裂，裂变fusion熔合，聚变constituents成分，组分accelerators加速器detectors 检测器★quarks夸克lepton 轻子gauge bosons规范玻色子gluons胶子★Higgs boson希格斯玻色子CERN欧洲核子研究中心★Magnetic Resonance Imaging磁共振成像，核磁共振ion implantation 离子注入radiocarbon dating放射性碳年代测定法geology地质学archaeology考古学stellar 恒星cosmology宇宙论celestial bodies 天体Hubble diagram 哈勃图Rival竞争的★Big Bang大爆炸nucleo-synthesis核聚合，核合成pillar支柱cosmological principle宇宙学原理ΛCDM modelΛ-冷暗物质模型cosmic inflation宇宙膨胀1 Physics 物理学fabricate制造，建造spintronics自旋电子元件，自旋电子学★neutrinos 中微子superstring 超弦baryon重子turbulence湍流，扰动，骚动catastrophes突变，灾变，灾难heterogeneous collections异质性集合pattern formation模式形成University Physics2 Classical mechanics 经典力学IntroductionIn physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces. The study of the motion of bodies is an ancient one, making classical mechanics one of the oldest and largest subjects in science, engineering and technology.Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. Besides this, many specializations within the subject deal with gases, liquids, solids, and other specific sub-topics.Classical mechanics provides extremely accurate results as long as the domain of study is restricted to large objects and the speeds involved do not approach the speed of light. When the objects being dealt with become sufficiently small, it becomes necessary to introduce the other major sub-field of mechanics, quantum mechanics, which reconciles the macroscopic laws of physics with the atomic nature of matter and handles the wave–particle duality of atoms and molecules. In the case of high velocity objects approaching the speed of light, classical mechanics is enhanced by special relativity. General relativity unifies special relativity with Newton's law of universal gravitation, allowing physicists to handle gravitation at a deeper level.The initial stage in the development of classical mechanics is often referred to as Newtonian mechanics, and is associated with the physical concepts employed by and the mathematical methods invented by Newton himself, in parallel with Leibniz【莱布尼兹】, and others.Later, more abstract and general methods were developed, leading to reformulations of classical mechanics known as Lagrangian mechanics and Hamiltonian mechanics. These advances were largely made in the 18th and 19th centuries, and they extend substantially beyond Newton's work, particularly through their use of analytical mechanics. Ultimately, the mathematics developed for these were central to the creation of quantum mechanics.Description of classical mechanicsThe following introduces the basic concepts of classical mechanics. For simplicity, it often2 Classical mechanics 经典力学models real-world objects as point particles, objects with negligible size. The motion of a point particle is characterized by a small number of parameters: its position, mass, and the forces applied to it.In reality, the kind of objects that classical mechanics can describe always have a non-zero size. (The physics of very small particles, such as the electron, is more accurately described by quantum mechanics). Objects with non-zero size have more complicated behavior than hypothetical point particles, because of the additional degrees of freedom—for example, a baseball can spin while it is moving. However, the results for point particles can be used to study such objects by treating them as composite objects, made up of a large number of interacting point particles. The center of mass of a composite object behaves like a point particle.Classical mechanics uses common-sense notions of how matter and forces exist and interact. It assumes that matter and energy have definite, knowable attributes such as where an object is in space and its speed. It also assumes that objects may be directly influenced only by their immediate surroundings, known as the principle of locality.In quantum mechanics objects may have unknowable position or velocity, or instantaneously interact with other objects at a distance.Position and its derivativesThe position of a point particle is defined with respect to an arbitrary fixed reference point, O, in space, usually accompanied by a coordinate system, with the reference point located at the origin of the coordinate system. It is defined as the vector r from O to the particle.In general, the point particle need not be stationary relative to O, so r is a function of t, the time elapsed since an arbitrary initial time.In pre-Einstein relativity (known as Galilean relativity), time is considered an absolute, i.e., the time interval between any given pair of events is the same for all observers. In addition to relying on absolute time, classical mechanics assumes Euclidean geometry for the structure of space.Velocity and speedThe velocity, or the rate of change of position with time, is defined as the derivative of the position with respect to time. In classical mechanics, velocities are directly additive and subtractive as vector quantities; they must be dealt with using vector analysis.When both objects are moving in the same direction, the difference can be given in terms of speed only by ignoring direction.University PhysicsAccelerationThe acceleration , or rate of change of velocity, is the derivative of the velocity with respect to time (the second derivative of the position with respect to time).Acceleration can arise from a change with time of the magnitude of the velocity or of the direction of the velocity or both . If only the magnitude v of the velocity decreases, this is sometimes referred to as deceleration , but generally any change in the velocity with time, including deceleration, is simply referred to as acceleration.Inertial frames of referenceWhile the position and velocity and acceleration of a particle can be referred to any observer in any state of motion, classical mechanics assumes the existence of a special family of reference frames in terms of which the mechanical laws of nature take a comparatively simple form. These special reference frames are called inertial frames .An inertial frame is such that when an object without any force interactions (an idealized situation) is viewed from it, it appears either to be at rest or in a state of uniform motion in a straight line. This is the fundamental definition of an inertial frame. They are characterized by the requirement that all forces entering the observer's physical laws originate in identifiable sources (charges, gravitational bodies, and so forth).A non-inertial reference frame is one accelerating with respect to an inertial one, and in such a non-inertial frame a particle is subject to acceleration by fictitious forces that enter the equations of motion solely as a result of its accelerated motion, and do not originate in identifiable sources. These fictitious forces are in addition to the real forces recognized in an inertial frame.A key concept of inertial frames is the method for identifying them. For practical purposes, reference frames that are un-accelerated with respect to the distant stars are regarded as good approximations to inertial frames.Forces; Newton's second lawNewton was the first to mathematically express the relationship between force and momentum . Some physicists interpret Newton's second law of motion as a definition of force and mass, while others consider it a fundamental postulate, a law of nature. Either interpretation has the same mathematical consequences, historically known as "Newton's Second Law":a m t v m t p F ===d )(d d dThe quantity m v is called the (canonical ) momentum . The net force on a particle is thus equal to rate of change of momentum of the particle with time.So long as the force acting on a particle is known, Newton's second law is sufficient to。

advanced optical materials分区

Advanced Optical MaterialsIntroductionAdvanced optical materials are a class of materials that possess unique optical properties and are engineered to enhance light-matter interactions. These materials have revolutionized various fields such as photonics, optoelectronics, and nanotechnology. In this article, we will explore the different types of advanced optical materials, their applications, and the future prospects of this exciting field.Types of Advanced Optical MaterialsPhotonic CrystalsPhotonic crystals are periodic structures that can manipulate the propagation of light. They consist of a periodic arrangement ofdielectric or metallic components with alternating refractive indices. These structures can control the flow of light by creating energy bandgaps, which prohibit certain wavelengths from propagating through the material. Photonic crystals find applications in optical communication, sensing, and solar cells.MetamaterialsMetamaterials are artificially engineered materials that exhibit properties not found in nature. They are composed of subwavelength-sized building blocks arranged in a periodic or random manner. Metamaterials can manipulate electromagnetic waves by achieving negative refractive index, perfect absorption, and cloaking effects. These unique properties have led to applications in invisibility cloaks, super lenses, and efficient light harvesting.Plasmonic MaterialsPlasmonic materials exploit the interaction between light and free electrons at metal-dielectric interfaces to confine light at nanoscale dimensions. This confinement results in enhanced electromagnetic fields known as surface plasmon resonances. Plasmonic materials have diverse applications such as biosensing, photothermal therapy, and enhanced solar cells.Quantum DotsQuantum dots are nanoscale semiconductor crystals with unique optical properties due to quantum confinement effects. Their size-tunable bandgap enables them to emit different colors of light depending ontheir size. Quantum dots find applications in display technologies (e.g., QLED TVs), biological imaging, and photovoltaics.Organic Optoelectronic MaterialsOrganic optoelectronic materials are based on organic compounds that exhibit electrical conductivity and optical properties. These materials are lightweight, flexible, and can be processed at low cost. They find applications in organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and organic field-effect transistors (OFETs).Applications of Advanced Optical MaterialsInformation TechnologyAdvanced optical materials play a crucial role in information technology. Photonic crystals enable the miniaturization of optical devices, leading to faster and more efficient data transmission. Metamaterials offer possibilities for creating ultra-compact photonic integrated circuits. Plasmonic materials enable the development of high-density data storage devices.Energy HarvestingAdvanced optical materials have revolutionized energy harvesting technologies. Quantum dots and organic optoelectronic materials are used in next-generation solar cells to enhance light absorption and efficiency. Plasmonic nanoparticles can concentrate light in solar cells, increasing their power output. These advancements contribute to the development of sustainable energy sources.Sensing and ImagingThe unique optical properties of advanced optical materials make them ideal for sensing and imaging applications. Quantum dots are used as fluorescent probes in biological imaging due to their bright emissionand excellent photostability. Metamaterial-based sensors offer high sensitivity for detecting minute changes in refractive index ormolecular interactions.Biomedical ApplicationsAdvanced optical materials have significant implications in biomedical research and healthcare. Plasmonic nanomaterials enable targeted drug delivery, photothermal therapy, and bioimaging with high spatial resolution. Organic optoelectronic materials find applications in wearable biosensors, smart bandages, and flexible medical devices.Future ProspectsThe field of advanced optical materials is rapidly evolving with continuous advancements being made in material synthesis, characterization techniques, and device fabrication processes. Thefuture prospects of this field are promising, with potential breakthroughs in areas such as:1.Quantum Optics: Integration of advanced optical materials withquantum technologies could lead to the development of quantumcomputers, secure communication networks, and ultra-precisesensors.2.Flexible and Wearable Electronics: Organic optoelectronicmaterials offer the potential for flexible and wearable electronic devices, such as flexible displays, electronic textiles, andimplantable medical devices.3.Optical Computing: Photonic crystals and metamaterials may pavethe way for all-optical computing, where photons replace electrons for faster and more energy-efficient data processing.4.Enhanced Optoelectronic Devices: Continued research on advancedoptical materials will lead to improved performance and efficiency of optoelectronic devices such as solar cells, LEDs, lasers, andphotodetectors.In conclusion, advanced optical materials have opened up newpossibilities in various fields by enabling unprecedented control over light-matter interactions. The ongoing research and development in this field promise exciting advancements in information technology, energy harvesting, sensing and imaging, as well as biomedical applications. The future looks bright for advanced optical materials as they continue to revolutionize technology and shape our world.。

WC5（Invited）

Silicon Photonic Crystal Waveguide ModulatorsLanlan Gu 1, Wei Jiang 2, Xiaonan Chen 1, Ray T. Chen 1*Microelectronic Research Center, Department of Electrical and Computer Engineering,1. The University of Texas at Austin, Austin, TX 78758, USA2. Omega Optics Inc, Austin, TX 78758, USA*Email:***************.eduAbstractUltra-compact silicon-photonic-crystal-waveguide-based thermo-optic and electro-opticalMach-Zehnder interferometers have been proposed and fabricated. Thermal and electricalsimulations have been performed. Experimental results were in a good agreement with thetheoretical prediction.IntroductionThe driving force behind the development of silicon photonics is the monolithic integration of optics and microelectronics. Silicon remains the dominant material for microelectronics ever since the invention of the integrated circuit. Silicon-on-insulator (SOI) has been identified as a promising material for integrated optoelectronics. CMOS circuits fabricated on SOI benefit from reduced parasitics and absence of latch-up problem, which enable high-speed and low-power operations. SOI also provides strong optical confinement for the telecommunication wavelengths serving as an ideal platform to realize the guided-wave micro- and nano- photonic devices. Silicon microelectronic devices have undergone numerous generations of feature size reduction. However, there has been little progress made in the miniaturization of the silicon based optical components. Photonic crystal provides a promising platform to build ultra-compact and high-performance photonic devices [1]. It has been demonstrated that the light propagation in a photonic crystal waveguide (PCW) can have much slower group velocity than that in the conventional waveguides [2]. Such a slow-photon effect greatly enhances the interaction between the light wave and the wave-guiding materials, namely, it amplifies the optical response of materials to the external fields, such as thermal and electrical fields. It thus potentially leads to a significant reduction in size and power consumption. In this paper, we present the simulation and experimental results for ultra-compact silicon-PCW-based thermo-optic (TO) and electro-optical (EO) Mach-Zehnder interferometers (MZIs).Results and discussionFor low-cost and low-frequency applications, the TO effect is considered an attractive alternative to the free-carrier EO effect for realization of optical switching and modulation [3, 4]. Silicon is an ideal material for implementing TO MZIs operating at 1.5µm mainly because: (1) silicon is transparent at this communication wavelength, (2) the TO coefficient is high in silicon, which is approximately 1.86 X10-4 K -1 , two times greater than polymers and twenty times greater than SiO 2 and Si 3N 4; (3) the thermal conductivity of silicon is also high, which is 100 times higher than SiO 2, and therefore it provides a comparatively fast switching speed. The microscope image of the fabricated silicon-PCW-based TO MZI is shown in Fig. 1 (a). This device was fabricated on a SOI wafer with a 220 nm-thick top silicon layer and a 2 µm-thick buried oxide layer. The pitch size of the hexagonal photonic crystal lattice is a = 400 nm. The normalized air hole diameter is designed to be (a)(b) Fig. 1 (a) Microscope image of the TO MZI;(b) Scanning electron microscope (SEM) image of a PCW at the 45o viewing angle.WC5 (Invited)18:00 – 18:30d/a = 0.53. Details of the fabrication were published in [5]. A Scanning electron microscope (SEM) image of the 45o -view of the PCW in conjunction with an input strip waveguide is shown in Fig. 1 (b). The length of photonic crystal waveguides is 80 µm. An aluminum thin-film micro-heater with the dimension of 8µm X100 µm was deposited on the silicon layer. It was on one side of the active arm of the MZI. A static thermal analysis of such a device was performed using a finite element modeling software, ANSYS. The simulated temperature profile across the device showed a temperature rise of 9o C in the line-defect region under an input ohmic heating power of 70 mW. It can be calculated, in a conventional silicon TO MZI, it requires an active region at least of 460 µm to obtain the π phase shift of the optical signal at 1.55 µm for a 9 o C temperature increase. Details of the calculation were previously reported [5]. However, in the PCW based MZI, the required length of the active region could be reduced significantly due to the amplification of TO effect in photonic crystals, which is intrinsically associated with the high-dispersion property of the PCW. We have experimentally demonstrated a size reduction of the silicon-PCW-based MZI by almost one order of magnitude compared with conventional TO MZIs [6].The modulation measurements were performed on afully-automated Newport Photonics Alignment/Packaging Station. The input and output lensed fibers canbe accurately aligned with silicon waveguides by twofive-axis high-precision stages with computerizedcontrol. TE waves were used for the opticalmeasurements. We chose wavelength at 1548nm, whichis at the edge of the defect mode, for the switchingproperty characterization. Switching characteristics wereobtained through a digital communication analyzer. Themeasured 3dB bandwidth was 30 kHz, which is a typicalvalue of a TO switch. The modulation curves at 1 kHzand 30 kHz are shown in Fig. 2 (a) and (b), respectively.The rise (10% to 90%) time and fall (90% to 10%) timewere measured to be 19 µs and 11 µs, respectively. It wasone order of magnitude faster than that was reported in aconventional structure with the micro-heater placed onthe top of the PCW region [7]. The maximummodulation depth of 84% was achieved at the switchingpower of 78 mW. The power consumption can bereduced by optimizing the heater geometry. It waspreviously shown by the ANSYS thermal simulation, asmall temperature variation of 9 o C was obtained in thePCW region with a supplied heat power of 70 mW. Itwould require an active region at least 460 µm to achieveπ phase shift in a conventional rib or strip waveguide based silicon TO MZI. Our experiments demonstrated almost a one-order of magnitude reduction in the lengthof the device active region, which obviously benefitedfrom the slow group-velocity of the PCW.The main drawback of the TO modulator is itscomparative low switching speed. A feasible way torealize high-speed optical modulation in the GHz domainis to utilize the EO effect instead of the TO effect. MostEO silicon modulators operate based on plasmadispersion effect. The relation between the variation ofthe refractive index and perturbation of free-carrierconcentration was studied by Scorf [8]. Here, wepropose a lateral p-i-n configuration for a PCW based EOMZI, which has a different structure from as previouslyreported [9]. In this device, index tuning was achieved using a forward biasing voltage to inject free carriers into photonic crystal region of the active arm. The switchingspeed of such a p-i-n diode based device is usually determined by the carrier recombination time or carrier transit time depending on which one is larger. The transient characteristics of the p-i-n diode were simulated using a (a) (b)Fig. 2 Modulation curves at (a) 1 kHz and (b) 30 kHz. Fig. 3 Transient free-carrier distributions along lateral distance of the p-i-n diode.two-dimensional semiconductor device simulator MEDICI. Thesimulated p-i-n device has an n-type background dopingconcentration of 1015 /cm 3 in the i region, whereas a uniformdoping concentration of 2X1019 /cm 3 was assumed for both p +and n + regions. The lateral electrodes were defined on top of thep + and n + regions, separated by 2µm from the PCW line defect.It is clearly shown in Fig. 3 that the minority carrier injection inthe intrinsic region, which is also the PCW region, is fairlyuniform. A carrier concentration perturbation of around 3X1017/cm 3, which induced a real refractive-index change of siliconabout -0.001, was predicted within 0.63ns under a forward biasing voltage of 2V. Further decrease of response time can be achieved by reducing the separation distance between the two lateral electrodes. For an index variation about 0.001, it usuallyrequires one-half to several millimeters active region to obtain the required π phase shift in the conventional rib waveguide based MZIs [10]. However, in our proposed PCW based MZI modulators, an active PCW region with a few tens of microns in length is long enough to achieve sufficient phase shift [9]. The microscope image of the fabricated p-i-n diode based silicon PCW MZI is shown in Fig. 4. As shown in Fig. 4, the p + and n + regions were carefully designed to avoid electrical breakdown at the fragile edges of photonic crystal waveguides and the advantages of such a design have been demonstrated in experiments. Extensive electrical and optical measurements is currently under investigation. More detailed experimental results will be presented at the conference.SummaryIn summary, we have proposed and fabricated ultra-compact silicon-PCW-based EO and TO MZIs. Device configurations were carefully designed based on the thermal and electrical simulations. The size of the silicon modulators was significantly reduced by incorporating the PCW into to MZIs. Both TO and EO devices have been fabricated and characterized.AcknowledgementsThis research is supported by AFOSR, DARPA’s AP2C program and NSF’s NNIN program. Technical advices from Dr. Gernot Pomrenke and Dr. Richard Soref are acknowledged.References[1]J. D. Joannopoulos, R. D. Meade, and J. Winn, Photonic Crystals , Princeton University Press, 1995. [2]M. Notomi, K. Yamada, A. Shinya, J. Takahashi, C. Takahashi, and I. Yokohama, “Extremely Large Group-Velocity Dispersion of Line-defect Waveguides in Photonic Crystal Slabs,” Phys. Rev. Lett ., 87, 253902 (2001). [3] G. Cocorullo, M. Iodice, I. Rendina, and P. M. Sarro, “Silicon thermaloptical micromodulator with 700-kHz-3-dBbandwidth ,” IEEE. Photonic technology letters , 7, 363 (1995).[4] Y. A. Vlasov, Martin O’Boyle, Hendrik F. Hamann, and S. J. McNab, “Active control of slow light on achip with photonic crystal waveguides,” Nature , 438, 65 (2005).[5]Lanlan Gu, Yongqiang Jiang, Wei Jiang, Xiaonan Chen, Ray T. Chen, “Silicon-on-insulator-based photonic-crystal Mach-Zehnder interferometers, ” Proceedings of SPIE, 6128, 261-268 (2006). [6]U. Fischer, T. Zinker, B. Schuppert and K. Petermann, “Singlemode optical switches based on SOI waveguides with large cross-section,” Electronics Letters , 30, 406 (1994). [7] Tao Chu, Hirohito Yamada, Satomi Ishida, and Yasuhiko Arakawa, “Thermooptic switch based on photonic-crystalline-defect waveguides,” IEEE. Photonic technology letters , 17, 2083 (2005).[8] R. A. Soref, B. R. Bennett, “Electrooptical effects in silicon,” IEEE J. Quantum Electron. QE-23, 123(1987).[9] Yongqiang Jiang, Wei Jian, Lanlan GU, Xiaonan Chen, Ray T. Chen, “80-micron interaction length silicon nano-photonic crystal waveguide modulator,” Applied Physics Letters , 87, 221105 (2005).[10] G.V. Treyz, P.G. May and J.M. Halbout, “Silicon Mach-Zehnder waveguide interferometers based on theplasma dispersion effect,” Appl. Phys. Lett ., 59, 771 (1991).Fig. 4 Microscope image of the top view of a p-i-n diode based photonic crystal silicon MZI.。

《2024年类EIT太赫兹超材料与可调控极化转换器的设计与研究》范文

《类EIT太赫兹超材料与可调控极化转换器的设计与研究》篇一一、引言在科技进步的今天，超材料成为了材料科学研究领域的热门方向，其在微波、毫米波和太赫兹频段等领域展现出巨大的应用潜力。

类电磁感应透明（EIT）效应超材料以其独特的物理特性和优越的调控性能在光学、光电子学以及通信等领域展现出重要的研究价值。

本篇论文旨在研究一种类EIT太赫兹超材料与可调控极化转换器，通过设计、制备和测试，探讨其性能和应用前景。

二、类EIT太赫兹超材料的设计与制备1. 设计思路类EIT效应是指光在介质中传播时，其电磁波在特定频率下表现出类似透明介质的行为。

本部分主要设计一种基于类EIT效应的太赫兹超材料，通过合理设计结构单元和排列方式，实现太赫兹波段的电磁波调控。

2. 制备方法采用微纳加工技术，如电子束蒸发、光刻、干法刻蚀等工艺，制备出具有特定几何形状和尺寸的超材料结构。

在制备过程中，严格控制各工艺参数，确保超材料的性能稳定和可靠性。

三、可调控极化转换器的设计与实现1. 设计思路可调控极化转换器是一种能够实现极化转换功能并具有可调谐特性的器件。

本部分设计一种基于类EIT太赫兹超材料的可调控极化转换器，通过改变超材料的结构参数或外部条件，实现极化转换的动态调控。

2. 实现方法采用电容加载、液晶调制等手段，实现极化转换器的可调谐特性。

在保持极化转换器的高效性和稳定性的同时，优化其动态调节范围和响应速度。

四、实验结果与分析1. 实验结果通过实验测试，验证了所设计的类EIT太赫兹超材料与可调控极化转换器的性能。

实验结果表明，该超材料在太赫兹波段表现出优异的电磁波调控性能，而可调控极化转换器则具有较高的极化转换效率和快速的动态调节能力。

2. 数据分析对实验数据进行详细分析，包括超材料的电磁波调控性能、极化转换器的极化转换效率以及动态调节范围等。

通过对比不同结构参数和外部条件下的性能变化，进一步揭示了所设计器件的物理特性和工作原理。

五、应用前景与展望1. 应用前景类EIT太赫兹超材料与可调控极化转换器在通信、雷达、生物医学等领域具有广泛的应用前景。

海洋相关多模态传感技术

海洋相关多模态传感技术
海洋相关的多模态传感技术是指利用多个传感器融合不同的感知模态，以获取更全面、准确的海洋信息的技术。

常用的海洋相关多模态传感技术包括以下几种：
1. 声学传感技术：利用声纳等装置探测海洋中的声音信号，用于测量海洋的物理参数、生物信息以及水下目标的探测等。

2. 光学传感技术：利用光学仪器、摄像头等获取海洋中的图像、视频信息，用于观察海洋生态环境、水下目标检测和成像等。

3. 电磁传感技术：利用电磁波传感器获取海洋中的电磁信号，用于测量海洋的电磁特性、水下目标探测和通信等。

4. 化学传感技术：利用化学传感器检测海洋中的化学成分和污染物，用于海洋水质监测、环境保护等。

5. 生物传感技术：利用生物传感器或生物学检测方法监测海洋中的生物信息，例如测量水中的藻类浓度、海洋生物的迁徙和分布等。

通过综合应用不同的传感器和技术，海洋相关的多模态传感技术可以实现对海洋环境的多维度、全方位的监测和观测，为海洋资源开发、环境保护、海洋科学研究等提供了重要的技术支持。

基于石墨烯的波束可重构太赫兹天线

通过对天线的基本性能和可调特性系统地模拟和优化数值结果表明通过改变加在石墨烯导向器的偏压天线的主辐射波瓣角方位角可以在30150的范围内进行扫描并且具有非常快的调制速度和非常低的回波损耗
第 39 卷第 1 期 2020 年 2 月
文章编号：1001-9014（2020）01-0039-08
红外与毫米波学报
sion line，a metallic reflector，a metallic half-round micro patch，and three groups of monolayer-graphene-patch directors. Because the conductivities of the graphene patches can be electrically tuned，the radiation direction of the QYU antenna can be dynamically controlled by adjusting the bias voltages applied to the graphene patches. The basic properties and the tunable behaviors of the antenna are systemically simulated and optimized. It has very fast modulation speed and very low return loss. In particular，the numerical results show that the main radia⁃ tion lobe angle φ（azimuth angle）of the QYU antenna can be swept from 30° to 150° in θ =60°（zenith angle） plane with different configurations of bias voltages applied to the graphene-patch directors. The proposed antenna is very suitable for THz beam reconfigurable applications，such as phased array radar systems. Key words：beam reconfigurable antenna，graphene，patch antenna，Yagi-Uda antenna PACS：84. 40. Ba， 87. 50. U-

高带外抑制特性微波陶瓷波导滤波器的设计

2021年4月Journal on Communications April 2021 第42卷第4期通信学报V ol.42No.4高带外抑制特性微波陶瓷波导滤波器的设计梁飞，蒙顺良，吕文中（华中科技大学光学与电子信息学院，湖北武汉 430074）摘要：介绍了陶瓷波导滤波器的设计理论，采用耦合通槽分别与浅、深耦合盲孔的组合结构来满足正、负耦合带宽要求，通过调整3～6腔体的交叉耦合来改善滤波器传输曲线的对称性，同时实现滤波器近端和远端的带外抑制，在此基础上设计了一款5G基站用六腔陶瓷波导滤波器。

在该滤波器的优化过程中，详细讨论了3～6腔体交叉耦合通槽的相对位置偏移量和交叉耦合通槽的长度对滤波器传输零点位置、近端和远端带外抑制特性的影响，并给出了相关的变化规律。

经优化后滤波器性能指标如下：中心频率为3.5 GHz，工作带宽为200 MHz，插入损耗≤1.2 dB，回波损耗≥17 dB，近端带外抑制≥25 dB，远端带外抑制≥51 dB。

根据仿真模型结构参数制备得到的样品，其性能测试结果与仿真结果吻合良好。

关键词：陶瓷波导滤波器；负耦合结构；交叉耦合通槽；带外抑制中图分类号：TN713文献标识码：ADOI: 10.11959/j.issn.1000−436x.2021029Design of microwave ceramic waveguide filter withhigh out-of-band suppression characteristicsLIANG Fei, MENG Shunliang, LYU WenzhongSchool of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China Abstract: The design theory of ceramic waveguide filter was introduced, and then the combination structure of coupling through slot with shallow or deep coupling blind hole was designed, which could meet the requirements of positive and negative coupling bandwidth. By adjusting the cross coupling between 3～6 cavities, the symmetry of the filter transmis-sion curve was improved, and the near and far end band suppression of the filter was realized. Finally, a six-cavity ce-ramic waveguide filter for 5G base station was designed. In the process of optimizing the filter, the influences of the rela-tive position offset of the cross-coupling through slot and the length of the cross-coupling through slot on the transmis-sion zero position, the near end and far end out of band suppression characteristics of the filter were discussed in detail, and the relevant change rules were given. The performance indexes of the optimized filter were as follows, center fre-quency was 3.5 GHz, working bandwidth was 200 MHz, insertion loss ≤ 1.2 dB, return loss ≥ 17 dB, near end out of band rejection ≥ 25 dB, far end out of band rejection ≥ 51 dB. According to the structural parameters of the simulation model, the performance test results of the samples are in good agreement with the simulation results.Keywords: ceramic waveguide filter, negative coupling structure, cross-coupling through slot, out-of-band suppression1引言随着5G通信时代的来临，大规模天线技术和有限的频谱资源对微波器件的尺寸、工作性能等各项指标都提出了更高的要求。

小波分析完美教程经典

函数。同样，连续小波变换(continuous wavelet transform，CWT )用下式表示，
∫ C(scale, position) = +∞ f (t)ψ (scale, position, t)dt −∞
这个式子的含义就是，小波变换是信号 f (t) 与被缩放和平移的小波函数ψ 之积在信号存在的整个期间里求和。CWT 变换的结果是许多小波系数 C ，这些系数是缩放因子(scale)和位
到真正的发展。小波变换的主要算法则是由法国的科学家 Stephane Mallat 在 1988 年提出[1]。他在构造
正交小波基时提出了多分辨率的概念，从空间上形象地说明了小波的多分辨率的特性，提出了正交小波的构造方法和快速算法，叫做 Mallat 算法[1]。该算法统一了在此之前构造正交小波基的所有方法，它的地位相当于快速傅立叶变换在经典傅立叶分析中的地位。
第 3 章小波与小波变换
(征求意见稿) 清华大学计算机科学与技术系智能技术与系统国家重点实验室
林福宗，2001-9-25
小波是近十几年才发展起来并迅速应用到图像处理和语音分析等众多领域的一种数学工具，是继 110 多年前的傅立叶(Joseph Fourier)分析之后的一个重大突破，无论是对古老的自然学科还是对新兴的高新技术应用学科都产生了强烈冲击。
图 3-02 傅立叶分析与小波分析使用的基函数数学上傅立叶分析的过程实际上是用傅立叶变换表示，
∫ F(ω) = +∞ f (t )e− jωtdt −∞
这个式子的含义就是，傅立叶变换是信号 f (t) 与复数指数 e− jωt ( e− jωt = cosωt + j sinωt )
之积在信号存在的整个期间里求和。傅立叶变换的结果是傅立叶系数 F(ω) ，它是频率ω 的

“自由探索类基础研究”优先支持内容

“自由探索类基础研究”优先支持内容1、基于人工智能的二维材料moiré超晶格制备技术研究内容：AI技术、深度机器学习技术等在人工精准堆叠层状半导体晶体、层状拓扑材料等功能材料异质结自动化纳米制备中的应用。

实现温度、角度、层数等至少3个自由度的人工智能堆垛技术，展示魔角石墨烯等转角精确可控的功能二维材料moiré超晶格的自动化制备原型样机。

考核指标：通过机器学习和图像视觉实现自动寻找二维目标材料，并完成光学显微镜自动对焦，误差优于1微米。

通过算法对硬件三维位移实现精确控制，自动实现二维材料转印过程，衍射牛顿环波前移动速率小于100微米/分钟。

实现至少2层二维材料的自动识别与堆叠，自动堆叠位移精度优于2微米，角度精度优于0.1度。

实现moiré超晶格2层及以上魔角石墨烯异质结的自动化制备，旋转角度控制在1.1至1.5度之间。

2、高均匀性晶圆键合加热技术研究内容：研究精密加热加压耦合承载平台、键合温度控制等内容，突破晶圆键合温度高均匀性、超大承载压力晶圆键合等关键技术，填补国内空白，解决行业领域和产业发展的关键核心技术问题，为集成电路晶圆键合类高端装备提供理论支撑和关键技术保障。

考核指标：晶圆加热平台8寸；最大承载压力100kN；最大键合温度500℃；温度均匀性±1%℃（温度测试点250℃、350℃、450℃，TC Wafer 9点测温）；控温精度：±1℃。

3、含氮马氏体不锈钢强化机制及关键制备技术研究内容：氮元素加入马氏体不锈钢后的存在形式、溶解度及与其它合金元素之间的内在联系、氮化物析出规律和转变机制、及微观组织演变；研究不同氮溶解度的情况下，氮化物的形貌、大小和分布等对高温力学性能和腐蚀行为的影响规律，揭示高温强化机制和腐蚀机理。

形成为设计和制备新型含氮不锈轴承钢支撑的原创性成果和关键技术。

考核指标：含氮马氏体不锈轴承钢（氮质量分数为0.10～0.20 wt.%）的抗拉强度≥1700MPa，屈服强度≥1300MPa，硬度值≥55 HRC；经100h的盐雾腐蚀不会发生点蚀破坏；含氮马氏体不锈轴承钢的自腐蚀电位高于无氮马氏体不锈轴承钢（-0.25V）。

小型化基片集成波导滤波器研究进展

• 36•小型化基片集成波导滤波器研究进展武警工程大学信息工程学院张怿成刘方毅孟志豪综述了基片集成波导滤波器小型化研究现状。

首先介绍了基片集成波导谐振器的基础理论，其次总结了基片集成波导谐振器小型化的实现方法和存在不足，最后对未来的发展趋势进行了展望。

引言：基片集成波导（Substrate Integrated Waveguide,SIW ）滤波器是一种新型结构器件，既具备了传统金属波导高品质因数、高功率等优点，又兼容了微带滤波器结构体积小、易集成的特点，在当今频谱环境日益紧张的通信系统中具有很高的研究和应用价值。

小型化基片集成波导滤波器有利于减少射频前端的体积，且便于和天线、功分器等微波器件相集成，是国内外学者研究的热点方向。

本文阐述了SIW 滤波器小型化的相关理论，介绍了其研究现状和发展趋势。

1 基片集成波导基础理论一般结构的SIW 谐振腔由金属层和介质层构成，腔体边缘周期性排列的的金属过孔可以等效为传统金属波导的侧壁，介质层通常选用Rogers RT/duroid 5880等材料，其结构如图1所示：图1 基片集成波导模型2005年，FengXu 在[Xu F,Wu K.Guided-wave and leakage characteristics of substrate integrated waveguide[J].IEEE Trans-actions on Microwave Theory & Techniques,2005,53(1):66-73]中给出了基片集成波导与金属波导的等效关系式：(1)且SIW谐振器的谐振频率可由下式确定：(2)其中m=1,2,3…, p=1,2,3…, ε为相对介电常数， μ为相对磁导率。

2 基片集成波导滤波器小型化方式SIW 滤波器的小型化技术可以分为三个方面：模切割技术、多层折叠技术、加载技术。

2.1 基于模切割技术的SIW小型化2005年，东南大学的洪伟教授在论文[Hong W,Liu B,Wang Y,et al.Half Mode Substrate Integrated Waveguide:A New Guided Wave Structure for Microwave and Millimeter Wave Application[C]//Joint,International Conference on Infra-red Millimeter Waves and,International Conference on Teraherz Electronics,2006.Irmmw-Thz.IEEE,2007:219-219]中提出了将全模SIW 沿中心线进行切割形成HMSIW ，其切口可等效于虚拟磁壁，既保留了前者的波导特性，又缩小了一半体积，其结构和场分布如图2所示。

基于传输线型超材料的激活太赫兹波导说明书

10.1117/2.1201308.005081 Active terahertz waveguides based on transmission-line metamaterialsBenjamin S.Williams,Amir Ali Tavallaee,Philip Hon,and Tatsuo ItohThe demonstration of a1D left-handed metamaterial waveguide for terahertz quantum-cascade lasers opens the door to new techniques for beam steering and shaping.Electromagnetic metamaterials are artiﬁcial structures that can be engineered to exhibit customizable or conventionally unob-tainable electromagnetic properties,such as propagation with near-zero or even negative refractive index.In a material with a negative index,theﬂow of energy is opposite to the move-ment of the wavefronts,an effect known as backward-wave or left-handed propagation(so named because the electricﬁeld, magneticﬁeld,and wavevector form a left-handed triple).At IR and optical frequencies,left-handed materials can be made by incorporating plasmonic structures into a dielectric.Pro-vided the size and periodicity of the structures is sufﬁciently small compared to the wavelength,waves propagate as if the medium were uniform with new values for the refractive index (or other bulk properties).Current research in this area investi-gates electromagnetic metamaterials for novel antenna concepts, sub-wavelength resonators and waveguides,superlenses that beat the diffraction limit,and even cloaking from electromag-netic radiation.Our research group has been working on methods to apply metamaterial concepts to the terahertz(THz)frequency range, where the wavelength is approximately a hundred times longer than in the visible.The novelty in our work is the combina-tion of metamaterial-inspired waveguides with a THz quantum-cascade laser-gain medium.In this way,stimulated emission of THz photons from intraband transitions in the gallium-arsenide-based medium compensates for losses and allows active devices.1To design and describe the metamaterial waveguide,we adopt the transmission-line formalism,where negativeand Figure1.Calculated dispersion relation for a balanced terahertz(THz) metamaterial waveguide exhibiting left-handed(LH)and right-handed (RH)propagation.GaAs:Gallium arsenide.AlGaAs:Aluminum gal-lium arsenide.p:Unit cell size.zero-index propagation are modeled by the introduction of additional lumped element capacitance and inductance into the series and shunt branches of the transmission line.2Where a conventional transmission line has series inductance L R and shunt capacitance C R,a metamaterial line is modeled by adding series capacitance C L and shunt inductance L L(the subscripts L and R stand for left-handed and right-handed propagation, respectively).We can adapt this scheme to THz quantum-cascade devices,which are fabricated into a metal-dielectric-metal waveguide.Figure1shows the calculated dispersion relation for a typical design with left-handed propagation be-low about2.6THz and right-handed propagation above2.6THz: a composite right-/left-handed(CRLH)metamaterial wave-guide.At2.6THz,the dispersion relation crosses between the two types of propagation,without a stopband,while maintain-ing non-zero group velocity.Such a condition is referred to as balanced and results from proper engineering of the effective capacitance and inductance on the transmission line.The key advance in this recent work is the inclusion of 200nm-size gaps in the top metallization of the waveguide:see Figure2.These gaps play the role of a series capacitance in theContinued on next page10.1117/2.1201308.005081Page2/2Figure 2.Image of a composite right-/left-handed metamaterial wave-guide implemented in a THz quantum-cascade (QC)metal-metal waveguide.The dielectric of this ‘transmission line’is made up of active THz QC gain material grown in GaAs/AlGaAs quantum wells.The inset image shows a close-up of 200nm gaps in the metallization that create the series capacitance C L and enable left-handed propagation.C x ,L x :Capacitors,inductors (where x denotes R or L).Cu:Copper.Cr:Chromium.Au:Gold.transmission-line model for the waveguide,and are the key fea-ture that enables left-handed propagation.We demonstrated the existence of left-handed propagation indirectly by using a sec-tion of the CRLH metamaterial waveguide as a leaky-wave cou-pling antenna for a THz quantum-cascade laser.The laser feeds the antenna with the THz signal,which is then radiated into the far-ﬁeld at an angle that depends on the THz frequency and its location on the dispersion diagram.While propagation in the right-handed region will result in a beam angled in the for-ward direction,propagation in the left-handed region generates a beam angled in the backward direction (off normal).Propaga-tion with a zero effective index (ˇD 0)gives a beam directed in the surface normal direction.Therefore,by measuring the far-ﬁeld beam pattern and the radiation frequency,we can recon-struct the dispersion relation:see Figure 1.We recently observed a backward-directed beam for the ﬁrst time,demonstrating the existence of left-handed propagation.3Beyond this proof of principle,we now have access to a wide array of microwave circuit,antenna,and metamaterial design techniques that can be applied to THz lasers.For example,such a metamaterial antenna could be used to steer a beam between the forward and backward directions (depending on the exact frequency).Or,if we can develop dynamic control of the circuit elements,tunable resonators and phase shifters become possi-ble.Our future work focuses on using these design techniques to create a new class of lasers with ﬂexible and dynamic control of spectral and radiation properties,including beam shaping and steering,wavelength tuning,and polarization state.Author InformationBenjamin S.Williams,Amir Ali Tavallaee,Philip Hon,and Tatsuo ItohUniversity of California at Los Angeles Los Angeles,CAReferences1.B.S.Williams,Terahertz quantum-cascade lasers ,Nat.Photon.1,pp.517–525,2007.i,C.Caloz,and T.Itoh,Composite right/left-handed transmission line metama-terials ,IEEE Microw.Mag.5,pp.34–50,2004.3.A.A.Tavallaee,P .W.C.Hon,Q.-S.Chen,T.Itoh,and B.S.Williams,Active terahertz quantum-cascade composite right/left handed metamaterial ,Appl.Phys.Lett.102,p.021103,2013.c2013SPIE。

Efficient design and optimization of photonic crystal waveguides and couplers The Interface Diffract

$Efficient design and optimization of photonic crystal waveguides and couplers The Interface Diffract$

Efﬁcient design and optimization ofphotonic crystal waveguides andcouplers:The Interface DiffractionMethodAlexander A.Green,Emanuel Istrate,and Edward H.SargentDepartment of Electrical and Computer Engineering,University of Toronto,Toronto,ONM5S3G4,Canadaaa.green@utoronto.caAbstract:We present the interface diffraction method(IDM),an efﬁcienttechnique to determine the response of planar photonic crystal waveguidesand couplers containing arbitrary defects.Field proﬁles in separate regionsof a structure are represented through two contrasting approaches:the planewave expansion method in the cladding and a scattering matrix method inthe core.These results are combined through boundary conditions at theinterface between regions to model fully a device.In the IDM,the relevantinterface properties of individual device elements can be obtained fromunit cell computations,stored,and later combined with other elements asneeded,resulting in calculations that are over an order of magnitude fasterthan supercell simulation techniques.Dispersion relations for photoniccrystal waveguides obtained through the IDM agree with the conventionalplane wave expansion method to within2.2%of the stopband width.©2005Optical Society of AmericaOCIS codes:(230.3990)Microstructure devices;(230.7370)Waveguides.References and links1.K.M.Ho,C.T.Chan,and C.M.Soukoulis,“Existence of a photonic gap in periodic dielectric structures,”Phys.Rev.Lett.65,3152–3155(1990).2.K.Busch and S.John,“Photonic band gap formation in certain self-organizing systems,”Phys.Rev.E58,3896–3908(1998).3.S.G.Johnson and J. D.Joannopoulos,“Block-iterative frequency-domain methodsfor Maxwell’s equations in a planewave basis,”Opt.Express8,173–190(2001)./abstract.cfm?URI=OPEX-8-3-173.4.S.G.Johnson,S.Fan,P.R.Villeneuve,J.D.Joannopoulos,and L.A.Kolodziejski,“Guided modes in photoniccrystal slabs,”Phys.Rev.B60,5751–5758(1999).5.K.S.Yee,“Numerical solution of initial boundary value problems involving maxwells equations in isotropicmedia,”IEEE Trans.Antennas Propag.14,302–307(1966).6. A.Taﬂove and S.C.Hagness,Computational Electrodynamics:The Finite-Difference Time-Domain Method(Artech House,Norwood,MA,2000).7.G.Bastard,“Superlattice band structure in the envelope-function approximation,”Phys.Rev.B24,5693–5697(1981).8. C.M.de Sterke and J.E.Sipe,“Envelope-function approach for the electrodynamics of nonlinear periodicstructures,”Phys.Rev.A38,5149–5165(1988).9. E.Istrate,M.Charbonneau-Lefort,and E.H.Sargent,“Theory of photonic crystal heterostructures,”Phys.Rev.B66(075121),075,121(2002).10.N.A.R.Bhat and J.E.Sipe,“Optical pulse propagation in nonlinear photonic crystals,”Phys.Rev.E64(056604),056,604–1–16(2001).#8231 - $15.00 USD Received 31 July 2005; revised 29 August 2005; accepted 30 August 2005 (C) 2005 OSA19 September 2005 / Vol. 13, No. 19 / OPTICS EXPRESS 730411.J.Poon,E.Istrate,M.Allard,and E.H.Sargent,“Multiple-scales analysis of photonic crystal waveguides,”IEEEJ.Quantum Electron.39(6),778–786(2003).12.J.P.Albert,D.Cassagne,and D.Bertho,“Generalized Wannier function for photonic crystals,”Phys.Rev.B61,4381–4384(2000).13.O.Painter,K.Srinivasan,and P.E.Barclay,“Wannier-like equation for the resonant cavity modes of locallyperturbed photonic crystals,”Phys.Rev.B68(035214),035,214(2003).14.K.Busch,S.F.Mingaleev,A.Garcia-Martin,M.Schillinger,and D.Hermann,“The Wannier function approachto photonic crystal circuits,”J.Phys.:Condens.Matter15,R1233–R1256(2003).15.K.Sakoda,Optical Properties of Photonic Crystals,chap.4(Springer,2001).16. E.Istrate,A.A.Green,and E.H.Sargent,“Behavior of light at photonic crystal interfaces,”Phys.Rev.B71(195122),195,122–1–7(2005).17. E.Istrate and E.H.Sargent,“Photonic Crystal Waveguide Analysis Using Interface Boundary Conditions,”IEEEJ.Quantum Electron.41,461–467(2005).18.T.Baba,N.Fukaya,and J.Yonekura,“Observation of light propagation in photonic crystal waveguides withbends,”Electron.Lett.35,654–655(1999).19.S.McNab,N.Moll,and Y.Vlasov,“Ultra-low loss photonic integrated circuit withmembrane-type photonic crystal waveguides,”Opt.Express11,2927–2938(2003)./abstract.cfm?URI=OPEX-11-22-2927.20. A.Adibi,R.K.Lee,Y.Xu,A.Yariv,and A.Scherer,“Design of photonic crystal optical waveguides withsinglemode propagation in the photonic band gap,”Electron.Lett.36,1376–1378(2000).21. A.Chutinan and S.Noda,“Waveguides and waveguide bends in two-dimensional photonic crystal slabs,”Phys.Rev.B62,4488–4492(2000).22.K.Yamada,H.Morita,A.Shinya,and M.Notomi,“Improved line-defect structures for photonic-crystalwaveguides with high group velocities,”mun.198,395–402(2001).23.Z.-Y.Li and K.-M.Ho,“Light propagation in semi-inﬁnite photonic crystals and related waveguide structures,”Phys.Rev.B68,155,101–1(2003).24.Z.-Y.Li and L.-L.Lin,“Photonic band structures solved by a plane-wave-based transfer-matrix method,”Phys.Rev.E67,046,607(2003).25.J.B.Pendry,“Photonic band structures,”J.Mod.Opt.41,209–229(1994).26.L.Lifeng,“Formulation and comparison of two recursive matrix algorithms for modeling layered diffractiongratings,”J.Opt.Soc.Am.A13,1024–1035(1996).27.S.Noda,A.Chutinan,and M.Imada,“Trapping and emission of photons by a single defect in a photonic bandgapstructure,”Nature(London)407(6804),608–610(2000).28.Y.Akahane,T.Asano,B.S.Song,and S.Noda,“High-Q photonic nanocavity in a two-dimensional photoniccrystal,”Nature(London)425(6961),944–947(2003).29. B.S.Song,S.Noda,T.Asano,and Y.Akahane,“Ultra-high-Q photonic double-heterostructure nanocavity,”Nat.Mater.4,207–210(2005).30.R. B.Lehoucq, D. C.Sorensen,and C.Yang,ARPACK Users’Guide:Solution of Large ScaleEigenvalue Problems with Implicitly Restarted Arnoldi Methods(SIAM,Philadelphia,1998)./software/ARPACK/.31. E.Anderson,Z.Bai,C.Bischof,S.Blackford,J.Demmel,J.Dongarra,J.D.Croz,A.Greenbaum,S.Ham-marling, A.McKenney,and D.Sorensen,LAPACK Users’Guide,3rd ed.(SIAM,Philadelphia,1999)./lapack/lug/index.html.32.S.Boscolo,M.Midrio,and C.G.Someda,“Coupling and decoupling of electromagnetic waves in parallel2-Dphotonic crystal waveguides,”IEEE J.Quantum Electron.38,47–53(2002).33. D.M.Whittaker and I.S.Culshaw,“Scattering-matrix treatment of patterned multilayer photonic structures,”Phys.Rev.B60,2610–2618(1999).34. A.R.Cowan,P.Paddon,V.Pacradouni,and J.F.Young,“Resonant scattering and mode coupling in two-dimensional textured planar waveguides,”J.Opt.Soc.Am.A18,1160–1170(2001).35.L.C.Andreani and M.Agio,“Photonic bands and gap maps in a photonic crystal slab,”IEEE J.QuantumElectron.38,891–898(2002).36.S.F.Mingaleev and K.Busch,“Scattering matrix approach to large-scale photonic crystal circuits,”Opt.Lett.28,619–621(2003).1.IntroductionPhotonic crystals provide aﬂexible platform for the realization of many optical components including passive,active,and nonlinear devices.Waveguides employing photonic crystals have been studied widely because they conﬁne light strongly and guide light over sharp bends with low losses.The complexity of the interaction between electromagnetic waves and these periodic#8231 - $15.00 USD Received 31 July 2005; revised 29 August 2005; accepted 30 August 2005 (C) 2005 OSA19 September 2005 / Vol. 13, No. 19 / OPTICS EXPRESS 7305structures,however,poses a large challenge for the intuitive,yet quantitative,understanding of their optical response.Because they are periodic,the behaviour of photonic crystals is completely and efﬁciently represented using a reduced-zone representation dispersion diagram[1,2,3]and its accompa-nying Bloch modes.These are calculated from the representation of the crystal in reciprocal space,working with the Fourier series of the dielectric constant.This Fourier space represen-tation,however,prevents the direct use of band structures and Bloch modes in the analysis and design of practical photonic crystal devices,which must necessarily be ofﬁnite size,and often incorporate deviations from periodicity.For waveguides,this problem has been overcome by the supercell method[4],where the waveguide including core and claddings is repeated peri-odically in order to allow a plane wave treatment.The periodic units,however,must be large enough to eliminate coupling between the parallel guides.Furthermore,the resulting modes must be inspected carefully in order to discard the unphysical modes with energy concentrated outside the core.The limitations of periodic representations are surmounted by theﬁnite-difference time-domain(FDTD)simulation method[5,6],one of the most common tools for the design of photonic crystal devices.FDTD simulations operate in real(direct)space and make few as-sumptions,if any,about the periodicity of the photonic crystal,enabling them to be applied to almost any structure.At the same time,however,these simulations are inefﬁcient since they cannot apply results from one crystal unit cell to identical neighbouring ones.Between the extremes of complete periodicity and aperiodicity exist a variety of methods that take advantage of the results obtained efﬁciently from the periodic parts of a device while allowing some deviation from this periodicity.Envelope approximations,similar in concept to their use with semiconductor heterostructures[7],have been used to calculate pulse propagation in a nonlinear crystal[8]and for photonic crystal heterostructures[9].Here the periodicity of each crystal section is used to extract a set of parameters describing the crystal in the same way as effective masses are used in ing these parameters,an envelope equation can be written that does not include the periodicities explicitly and is therefore easy to solve.A similar approach was taken using multiple-scales techniques[10,11].Point and line defects have also been represented using Wannier functions forming a localized basis,similar to the tight-binding formalism[12].Wannier functions have also been used to calculate the resonant states of graded resonant cavities[13]and to derive a set of optimally adapted functions for the simulation of waveguides and cavities[14].The resonance of light in photonic crystals of ﬁnite size has been computed with a plane wave expansion over the entire slab[15].All these methods replace Maxwell’s equations with a simpliﬁed set of equations to be solved in the partially periodic structure.We have recently introduced a method that uses the Bloch modes of inﬁnite photonic crys-tals to calculate the reﬂection,transmission,and diffraction of light at photonic crystal inter-faces[16].These coefﬁcients,similar to the Fresnel coefﬁcients for dielectric interfaces,can then be used to model photonic crystal devices that include interfaces between photonic crys-tals and homogeneous materials as a succession of effective materials,with propagation inside each material described by its respective band structure.This method has been shown to sim-ulate efﬁciently the response of point defect cavities,as well as line defect waveguides and waveguide couplers[17].So far this method has been limited by the fact that the devices could only contain large periodic sections,where the electromagneticﬁeld proﬁles took the form of the bulk crystal modes,and homogeneous materials,with plane wave propagation.Most photonic crystal waveguides and defect cavities demonstrated so far are obtained by removing one cylinder,or a row of cylinders from a periodic2D crystal[18,19].In the process of optimizing the properties of these waveguides and resonant cavities,it was found that sig-#8231 - $15.00 USD Received 31 July 2005; revised 29 August 2005; accepted 30 August 2005 (C) 2005 OSA19 September 2005 / Vol. 13, No. 19 / OPTICS EXPRESS 7306niﬁcant advantages can be obtained by the introduction of more elaborate defects.The rows of cylinders adjacent to the missing rows can,for example,be modiﬁed to affect the propagation in the core[20].Alternatively,the cylinders in the core do not have to be removed completely, as long as their diameter is changed[21,22].Transfer and scattering matrices have been used to model the transmission and reﬂection from photonic crystals that are periodic in two directions but not necessarily in the third.The same matrices have been used to compute the interaction of light with semi-inﬁnite photonic crystals[23].In this paper we demonstrate that simulations conducted over photonic crystal unit cells alone are sufﬁcient to determine the response of photonic crystal waveguides and couplers with complex defect ing our technique,which we refer to as the interface diffraction method(IDM),individual device elements,such as a row of cylindrical defects of a particular radius or a bulk crystal region,can be simulated independently and combined as needed to model a device.In contrast,the supercell waveguide simulation techniques described earlier require computational domains consisting of many unit cells and must be done on a case-by-case basis for even small changes in structure.The IDM also makes few assumptions about the crystal geometry and defect type,making it more general than other approaches.It can be applied to narrow or wide defect regions with abrupt or graded changes in structure,all within the same theoretical framework without large increases in computation time.Moreover,the IDM achieves its computational beneﬁts through conceptually simple ingredients–the plane wave expansion and scattering matrix methods–that can be obtained through a variety of different techniques.With the IDM,we take advantage of the respective strengths of reciprocal and real space methods to model different waveguide regions.For the periodic parts of the device we use Bloch modes obtained from a plane wave expansion[16].The parts of the structure with de-viations from periodicity are simulated using a plane wave based scattering matrix approach described in Ref.[24].The photonic crystal Fresnel coefﬁcients are used to link the two sim-ulation methods allowing very efﬁcient modelling of structures with arbitrary geometries.In this paper,we demonstrate theﬂexibility of the IDM with several types of photonic crystal waveguides and a novel coupler design,at each step verifying its accuracy with comparisons to numerical simulations.2.Theory2.1.Bloch mode and scattering matrix interfaceOur method of simulating waveguides divides the devices into periodic cladding and aperiodic core regions connected through inﬁnitesimally thin homogeneous material layers.Inside the photonic crystal claddings,ﬁelds are described by a superposition of Bloch modes that excite a series of diffracted plane waves inside the core-cladding interface layer.These plane waves propagate into the core and produce a set of reﬂected and transmitted waves whose amplitudes are related through a scattering matrix.In the following discussion,we employ a planar photonic crystal waveguide oriented as il-lustrated in Fig.1,with the dielectric slab parallel to the xy-plane and the waveguide extending along the x-direction.The vectorsˆx,ˆy,andˆz are the Cartesian unit vectors.The Bloch modes of the photonic crystal cladding are calculated using the plane wave expansion method introduced in Ref.[16].In this method,we specify the angular frequencyω,the lateral wave vector k0, , and the normal vectorˆn to a given interface to obtain a set of Bloch modes with these prop-erties and their corresponding complex wave vector components alongˆn.For a core-cladding interface parallel to the xz-plane,k0, =k0,xˆx+k0,zˆz,ˆn=ˆy,and the resulting complex wave vectors are k B±j=k0, +k B±j,yˆy,where±indicates the direction of propagation or decay of the #8231 - $15.00 USD Received 31 July 2005; revised 29 August 2005; accepted 30 August 2005 (C) 2005 OSA19 September 2005 / Vol. 13, No. 19 / OPTICS EXPRESS 7307Bloch mode alongˆy,j labels each of the modes at a given frequency,and k B±j,y are the complex wave vector components.Thus crystal modes calculated from this method provide a complex band structure composed of Bloch wave vectors with real and imaginary parts.Inside the crys-tal passbands,the band structure has some modes with purely real wave vectors corresponding to freely propagating Bloch modes and others with complex wave vector components charac-terizing the exponential decay rates of evanescent Bloch modes.Inside the photonic crystal stopbands,the band structure consists entirely of evanescent modes.We represent theﬁelds inside the cladding with a superposition of these Bloch modes given by the following equation:E B(r)=∑j ∑αξBαj∑l,m,nE Bαjlmn expik Bαj+G lmn·r,(1)whereαis either+or−;G lmn are the reciprocal lattice vectors speciﬁed through indices l,m,and n;E Bαjlmn are the Fourier components of the Bloch modes;andξBαj are the amplitudecoefﬁcients of the Bloch modes.Fig.1.Schematic illustration of the IDM viewing a planar triangular photonic crystal devicefrom above.The core and cladding areas are separated by thin interface layers.The dashedrectangles mark the simulation cells used for each device region.To model two-dimensionally patterned slab waveguides in our3D plane wave expansion, we simulate a3D unit cell with artiﬁcial periodicity normal to the slab plane[4].Despite the unphysical nature of this approach,extending the cell in the vertical direction can effectively eliminate the interaction of conﬁned modes with neighbouring slabs because these modes de-cay exponentially above and below the slab.Although we do form a supercell in the vertical direction for these simulation cells,they are still much smaller than the supercells used in other methods,which are extended both laterally and vertically.For a planar photonic crystal with a square lattice of holes,we employ an extended unit cell of height h in the z-direction and of length a in the x-and y-directions.This crystal has a set of reciprocal lattice vectors given by:G lmn=l b2+m b1+n b3where b1=2πa−1ˆx,b2=2πa−1ˆy,and b3=2πh−1ˆz.At the core-cladding interface,the Bloch modes excite a set of diffracted waves in the homogeneous interface layer that are periodic over the interface plane:E h(r)=∑m,nE+mn exp(ik mn,y y)+E−mn exp(−ik mn,y y)expik0, +G mn,·r,(2)(C) 2005 OSA19 September 2005 / Vol. 13, No. 19 / OPTICS EXPRESS 7308 #8231 - $15.00 USD Received 31 July 2005; revised 29 August 2005; accepted 30 August 2005where G mn , =(G lmn ·ˆx )ˆx +(G lmn ·ˆz )ˆz =2πma −1ˆx +2πnh −1ˆz is the set of reciprocal lattice vec-tors projected onto the interface plane,r =x ˆx +z ˆz ,and k mn ,y =[(n h ω/c )2−|k 0, +G mn , |2]1/2in a homogeneous layer of index n h .The application of boundary conditions over the interface ensures that coupling occurs only between Bloch modes and plane waves with the same propagation constant in the core-cladding interface plane and yields the following set of equations for each diffraction order:∑j B +jmn ,x B −jmn ,x B +jmn ,z B −jmn ,z ξB +j ξB −j = E +mn ,x E +mn ,z + E −mn ,x E −mn ,z ,(3)∑jC +jmn ,x C −jmn ,x C +jmn ,z C −jmn ,z ξB +j ξB −j =1k mn ,y k x k z ω2−k 2x k 2z −ω2−k x k z E +mn ,x E +mn ,z − E −mn ,x E −mn ,z ,(4)where k x =k 0,x +G lmn ·ˆx =k 0,x +2πma −1and k z =k 0,z +G lmn ·ˆz =k 0,z +2πnh −1.The elements B ±jmn ,x /z and C ±jmn ,x /z on the left side of Eqs.(3)and (4)reﬂect the electric and magnetic ﬁeld amplitudes of the crystal modes at the plane y =y 0in the unit cell and are deﬁned:B ±jmn=∑l E B ±jlmn exp iG l ,⊥y 0 ,(5)C ±jmn =∑l (k B ±j +G lmn )×E B ±jlmn exp iG l ,⊥y 0 ,(6)where G l ,⊥=G lmn ·ˆy =2πla −1is the set of reciprocal lattice vectors projected onto ˆn .With column vectors E +B =(···,ξB +j ,ξB +j +1,···)T ,E −B =(···,ξB −j ,ξB −j +1,···)T ,E +=(···,E +mn ,x ,E +mn ,z ,···)T ,and E −=(···,E −mn ,x ,E −mn ,z ,···)T ,we can combine Eqs.(3)and (4)to form the transfer matrix T containing the diffraction coefﬁcients required to compute the set of plane waves excited by an arbitrary combination of Bloch modes in the cladding:E +E − =T E +B E −B = T 11T 12T 21T 22 E +B E −B.(7)The scattering matrix for the interface,which describes the outgoing modes produced by an arbitrary set of incoming ones,can be readily derived from the elements of the transfer ma-trix [25,26].After calculating the transfer matrix describing the waveguide at the cladding to homoge-neous material interface,we can simulate the remaining core region of the device using the plane wave based scattering matrix method described in Ref.[24].In this approach,a dielec-tric structure with transverse periodicity is divided along the propagation direction into slices separated by inﬁnitesimally thin homogeneous ﬁlms.For the dielectric slices,we calculate the scattering matrices relating the diffracted plane waves excited in the two ﬁlms surrounding each slice.Applying the usual scattering matrix recursion formulae [25,26]to each of the matrices yields the scattering matrix for the entire structure.The scattering matrix S for the waveguide determines the set of outgoing plane waves E −L and E +R from the core produced by an arbitrary set of waves E +L and E −R incident on the core:E +R E −L =S E +L E −R = S 11S 12S 21S 22 E +L E −R.(8)We can now determine the properties of the entire waveguide structure using the S -matrices and T -matrices describing the behaviour of light at the homogeneous boundaries of the core and cladding regions.(C) 2005 OSA19 September 2005 / Vol. 13, No. 19 / OPTICS EXPRESS 7309#8231 - $15.00 USD Received 31 July 2005; revised 29 August 2005; accepted 30 August 2005puting waveguide dispersion relationsResonant states reﬂecting conﬁned waveguide modes exist when theﬁeld proﬁle of light insidethe core is unchanged following a round-trip from one edge of the core to the other.To deter-mine the round-trip change in theﬁeld,we examine theﬁelds at the core-cladding interface anddivide the propagation into two distinct phases.In theﬁrst phase,an incident set of plane-wavesE−L in one of the interface planes strikes the cladding producing a reﬂected set of waves E+L.Since the cladding is semi-inﬁnite and the frequencies of interest are inside the the photoniccrystal’s stopband,any incident Bloch mode will have decayed to zero at the core-claddinginterface,hence E+B=0.This condition enables the incident and reﬂectedﬁelds to be related simply through E+L=T12T−122E−L.In the second phase,theﬁrst reﬂected set of waves propa-gates through to the other side of core,reﬂects off the cladding,and propagates back throughthe core.The relationship between incident E+L and reﬂected E −L waves in this case is given byE −L=[S12+S11T12(T22−S21T12)−1S22]E+L.Applying the resonant state condition E −L=E−L yields the following:E−L=S12+S11T12(T22−S21T12)−1S22T12T−122E−L.(9)We can solve Eq.(9)as an eigenvalue problem noting that resonant states for the waveguideoccur when an eigenvalue of the system equals one.For waveguides that are symmetric about the centre plane of the core,guided modes canbe divided into even and odd classes with respect to the mirror plane normal to the slab.Forresonant states in this case,theﬁeld proﬁles in the two core-cladding interfaces must satisfyE+R=±E−L and E+L=±E−R.Applying symmetry considerations to the scattering matrix and propagating the plane waves across to the other side of the core,we arrive at the followingguided mode condition:E−L=±1−S12T12T−122−1S11T12T−122E−L.(10)Eq.(10)can also be solved as an eigenvalue problem with even and odd guided modes obtained for eigenvalues equal to+1and−1,respectively.To implement the eigenvalue equations above,we obtain the T-matrices governing the reﬂec-tion from the claddings and the S-matrices describing propagation through the core at a given k0, and a number of frequency points inside the stopband.These matrices have no variable elements and thus Eqs.(9)and(10)can be solved using standard computational techniques. After calculating eigenvalues over a series of frequencies,we can interpolate their phase and magnitude toﬁnd the resonant states of the system at a veryﬁne frequency resolution.In prac-tice,the matrices in Eqs.(9)and(10)are well-conditioned and their dimensions are not large, with several hundred elements in3D simulations and under100elements in2D,enabling ex-act eigenvalues to be obtained in seconds.The eigenvalues from Eq.(9)have magnitudes that typically vary little over the stopband while those of Eq.(10)tend to vary rapidly.Both sets of eigenvalues usually have phases that vary smoothly over the stopband.As a result,we prefer to employ Eq.(9)for our simulations since interpolation is simpler and faster,and use Eq.(10)to gain general information about the symmetry of the modes.It is also possible to directly combine the S-and T-matrices deﬁned in subsection2.1to com-pute dispersion relations.In this approach,we determine the transmission through the cladding-core-cladding structure in the direction normal to the waveguide.This method,however,proves to be inefﬁcient since Bloch modes and scattering matrices at many frequencies are required to discern the very abrupt peaks in transmission that mark resonant states.(C) 2005 OSA19 September 2005 / Vol. 13, No. 19 / OPTICS EXPRESS 7310 #8231 - $15.00 USD Received 31 July 2005; revised 29 August 2005; accepted 30 August 20052.3.Core and cladding modiﬁcationsOnce the scattering and transfer matrices for different core and cladding regions are obtained,waveguide elements can be combined arbitrarily to yield new designs.The scattering matrices for core regions consisting of several rows of defects can be formed from those of a single row defect using the scattering matrix recursion formulae [25,26].Another degree of freedom can be achieved by displacing the cladding and core elements along the waveguide propagation direction.For core region unit cells,the translation is performed by introducing a phase shift into the incoming and outgoing plane wave coefﬁcients to compensate for the relative positionsof neighbouring unit cells.For a translation r 0, =x 0ˆx +z 0ˆz in the xz -plane,the shifted scattering matrix S is related to the original matrix S through:S = e −i G ·r 0, 00e −i G ·r 0, S e +i G ·r 0, 00e +i G ·r 0,,(11)where e ±i G ·r 0, is a diagonal matrix with diagonal elements exp (±i G mn , ·r 0, ).Similarly,translations of the cladding unit cells are accomplished through the following operation:T = e +i G ·r 0, 00e +i G ·r 0,T ,(12)where T and T are the initial and shifted matrices,respectively.3.ResultsIn this section,we apply the IDM to a variety of different photonic crystal waveguide designs.The bulk crystal in each of these waveguides consists of a triangular lattice of air holes etched in a high index slab.In our ﬁrst example,we determine the response of a full 3D planar photonic crystal waveguide with a defect row of air holes.In the subsequent examples,we focus on 2D waveguides to facilitate comparison with other methods.3.1.3D slab waveguideThe properties of photonic crystal waveguides can be tuned using different air hole defects inside the core.In the waveguide we study here,the bulk crystal consists of holes of radius 0.29a ,where a is the lattice constant,etched into a dielectric membrane of thickness 0.6a and index 3.4.This particular crystal structure has been successfully fabricated and used in waveguides [27]and high-quality factor cavities [28,29].It possesses a band gap ranging from 0.261c /a to 0.331c /a for even modes with respect to the in-slab mirror plane.The waveguide core is formed by reducing the radii of a row of holes to 0.2a ,establishing a line defect capable of guiding light (Fig.2(a)).To determine the properties of the waveguide,we obtain the Bloch modes and scattering matrices for its unit cell components.The bulk crystal Bloch modes are simulated using a computational cell of height 4a and length √3a with orthog-onal axes (Fig.1)and an expansion of 1575plane waves.The resulting eigenvalue equation is solved using an implementation of the implicitly restarted Arnoldi method (IRAM)[30]tuned to ﬁnd the Bloch modes with the slowest decay rates.The matrices in these computations are well-conditioned and generally require fewer than 20IRAM iterations to obtain Bloch modes converged to machine precision.The core region scattering matrices are obtained from a cell of the same height but of length √3/2a with an expansion of 128diffracted waves.To compute the dispersion relation (Fig.2(b)),we form the transfer matrix using seven to ten evanescent Bloch modes and employ Eq.(9)to ﬁnd the resonant states.In practice,it is rare to ﬁnd resonant states where an eigenvalue is identically equal to one.Instead we employ a (C) 2005 OSA19 September 2005 / Vol. 13, No. 19 / OPTICS EXPRESS 7311#8231 - $15.00 USD Received 31 July 2005; revised 29 August 2005; accepted 30 August 2005。

可重构偏振调控型表面等离激元定向耦合

2014年8月·综合科学中国人 15
袁小聪教授
南开大学电子信息与光学工程学院
南开大学现代光学所教授，信息科学技术学院副院长。

获得天津大学光
学工程专业本科（1985年）及工学硕士（1988年）学位，伦敦大学物理学
博士学位（1994年），剑桥大学博士后（1994-1999年）。

1999-2008年在
新加坡南洋理工大学微电子系任教。

在海外获得15项科研项目并担任负责
人，包括一项重大基础研究项目，共计科研经费合人民币约四千余万元。

已
发表SCI收录的论文120余篇，多次在国际光学工程学会(SPIE)和美国光学学会
(OSA)年会作微光学、光学显微成像与传感、光镊等方面邀请报告。

光学学术
期刊《Optics & Photonics Letters》主编，《中国光学与应用光学》副主编。

鉴
于其在微纳光学领域的贡献，分别于2005年和2009年被选为SPIE Fellow和OSA
Fellow。

可重构偏振调控型表面等离激元定向耦合
文章提出了一种全新的S P P s耦合方式，通过一系列亚波长“人”字型微纳金属结构，解决了目前入射光偏振态严重影响SPPs耦合效率以及SPP传播方向无法精确控制等技术难题，实现了SPPs的可重构定向耦合新机制，该研究成果对微纳光子芯片水平的S P P s产生、传输、调控、互联与探测等应用有重大积极推进作用，为未来发展S P P s大规模光电子集成与互联技术奠定了基础。

全息波导耦出光栅出瞳亮度均匀性的改善说明书

文章编号：1005-5630(2020)04-0014-06DOI : 10.3969/j.issn.1005-5630.2020.04.003全息波导耦出光栅出瞳亮度均匀性的改善王婉秋，任雪畅，炉庆洪，刘凯航（厦门大学物理科学与技术学院，福建厦门 361005）摘要：目前在AR 领域，存在着全息波导显示系统的耦出光栅出瞳亮度不均匀的问题，设计并制作了一种衍射效率渐变的全息光栅以进一步提高显示光路中耦出光栅的出瞳亮度均匀性。

提出移动遮挡板方案，以实现分区域地改变全息干版的曝光时间，使得到的全息光栅的衍射效率具有渐变特性，并对实验结果进行研究和分析。

结果表明，系统中耦出光栅的出瞳亮度均匀性由28.57%提高到57.14%。

因此采用的全息光学元件的拍摄光路和曝光方法，可以有效改善全息波导耦出光栅出瞳亮度均匀性。

关键词：全息波导；衍射效率；耦出光栅；亮度均匀性中图分类号：O 438.1 文献标志码：AImprovement of brightness uniformity of out-couplinggrating in holographic waveguideWANG Wanqiu ，REN Xuechang ，LU Qinghong ，LIU Kaihang（College of Physical Science and Technology, Xiamen University, Xiamen 361005, China ）Abstract: At present, there is a problem of uneven brightness of the out-coupling grating of the holographic waveguide display system in the field of AR. In this paper, a holographic grating with a diffractive efficiency gradient is designed and fabricated to further improve the brightness uniformity of out-coupling grating in the display optical path. Based on theoretical analysis and discussion, this paper proposes a scheme of moving the shutter to realize the change of the exposure time of the holographic plate by divisional region, so that the diffraction efficiency of the obtained holographic grating has a gradual characteristicThe final experimental results are studied and analyzed. The results show that the uniformity of the exit pupil brightness of the coupled grating in the system increases from 28.57% to 57.14%. Therefore, the photographic optical path and exposure method of the holographic optical element used in this paper can effectively improve the uniformity of the exit pupil brightness of the holographic waveguide coupling out grating.Keywords: holographic waveguide ；diffraction efficiency ；out-coupling grating ；brightness uniformity收稿日期：2019-11-25作者简介：王婉秋(1995—)，女，硕士研究生，研究方向为全息光学中光栅结构、光学器件和计算全息编码。