Mode-locked quantum-dot lasers 锁模量子点激光器
半导体锁模激光器的英语
半导体锁模激光器的英语Semiconductor Mode-Locked Lasers.Semiconductor mode-locked lasers (MLLs) are a type of laser that emits pulses of light with extremely short durations, typically in the picosecond or femtosecond range. They are based on semiconductor materials, such as gallium arsenide (GaAs) or indium phosphide (InP), and use avariety of techniques to achieve mode-locking, which is the process of synchronizing the longitudinal modes of thelaser cavity.Mode-locked lasers are widely used in a variety of applications, including optical communications, optical sensing, and laser processing. They are particularly useful in applications that require high peak powers and short pulse durations, such as in nonlinear optics and ultrafast spectroscopy.There are several different techniques that can be usedto achieve mode-locking in semiconductor lasers. One common technique is to use an external cavity, which consists of a laser diode and an external resonator. The laser diode is used to generate the optical gain, while the external resonator is used to provide feedback and control the mode-locking process. Another technique is to use a saturable absorber, which is a material that absorbs light at low intensities but becomes transparent at high intensities.The saturable absorber is placed inside the laser cavityand acts to selectively suppress certain modes of the laser, leading to mode-locking.The performance of semiconductor MLLs is characterized by a number of parameters, including the pulse duration,the repetition rate, the average power, and the peak power. The pulse duration is the duration of the individual light pulses, and is typically measured in picoseconds or femtoseconds. The repetition rate is the rate at which the pulses are emitted, and is typically measured in gigahertz. The average power is the average power of the laser output, and is typically measured in milliwatts or watts. The peak power is the maximum power of the individual light pulses,and is typically measured in kilowatts or megawatts.Semiconductor MLLs are a rapidly developing field, and new advances are being made all the time. These lasers are becoming increasingly powerful and efficient, and arefinding new applications in a wide variety of fields.半导体锁模激光器。
基于石墨烯可饱和吸收的锁模光纤激光器研究
基于石墨烯可饱和吸收的锁模光纤激光器研究陈恺;祝连庆;姚齐峰;骆飞【摘要】An all-polarization-maintaining erbium-doped Q-switched mode-locked fiber laser by graphene saturable absorber mirror was reported.The characteristics of Q-switched mode-locked laser with monolayer graphene as saturable absorber were studied,and the laser output was obtained at the center wavelength of 1557.69 nm.Repetition rate of Q-switched envelope varied from 11.49 to 40.41 kHz,and the width of Q-switched envelope varied from 10.1 to 3.62 μs.When the inciden t pump power is 191.3 mW,the maximum average output power of the laser is 9.354 mW and the maximum light-light conversion efficiency is 4.89 ％.%报道了一种基于单层石墨烯可饱和吸收体调Q锁模的全保偏结构掺铒光纤激光器.研究了单层石墨烯作为可饱和吸收体实现调Q锁模后的激光特征,获得了中心波长1557.69 nm 的激光输出.调Q锁模脉冲包络重复频率11.49 ～ 40.41 kHz范围变化,包络宽度在10.1 ～3.62 μs范围变化.在泵浦功率为191.3 mW时,激光器最大输出平均功率9.354 mW,最大光-光转换效率为4.89％.【期刊名称】《激光与红外》【年(卷),期】2017(047)003【总页数】5页(P291-295)【关键词】调Q锁模光纤激光器;全保偏光纤结构;石墨烯饱和吸收镜【作者】陈恺;祝连庆;姚齐峰;骆飞【作者单位】北京信息科技大学光电信息与仪器北京市工程研究中心,光电测试技术北京市重点实验室,北京100016;北京信息科技大学光电信息与仪器北京市工程研究中心,光电测试技术北京市重点实验室,北京100016;北京信息科技大学生物医学检测技术及仪器北京实验室,北京100192;北京信息科技大学光电信息与仪器北京市工程研究中心,光电测试技术北京市重点实验室,北京100016;北京信息科技大学光电信息与仪器北京市工程研究中心,光电测试技术北京市重点实验室,北京100016【正文语种】中文【中图分类】TN248脉冲光纤激光器具有结构紧凑、体积小、泵浦效率高、光束质量好等优势,广泛应用在加工、通讯、医疗等领域。
调Q锁模运转的全固态TmLuAG陶瓷激光器
第50卷第4期V〇1.50No.4红外与激光工程Infrared and Laser Engineering2021年4月Apr.2021调Q锁模运转的全固态T m:L uA G陶瓷激光器陈晨1二3,许强i孙锐1A张亚妮康翠萍\张明霞2,袁振2,令维军2(1.宝鸡文理学院物理与光电技术学院，陕西宝鸡721016;2.天水师范学院激光技术研究所，甘肃天水741001;3.宝鸡市超快激光和新材料工程技术研究中心，陕西宝鸡721016;4.陕西科技大学文理学院，陕西西安710021)摘要：采用垂直生长法制备的氧化石墨浠（Grapheneoxide，GO)作为可饱和吸收体，利用典型“X”型折叠腔在全固态Tm:Lu3Al5012(Tm:LuAG)陶瓷激光器中实现了调Q锁模运转。
以790 nm激光二极 管（Laser diode,LD)作为泵浦源，当泵浦功率大于8 W时，激光器进入稳定的调Q锁模状态。
当输出 镜透过率为5%时，连续光最高输出功率为714 mW,斜效率为4.94%。
当泵浦达到16 W时，激光器最 大输出功率为200 mW,光谱中心波长为2024 nm,脉冲宽度约为695 ps,对应的锁模脉冲重复频率为 108.7 MHz,调Q包络中锁模脉冲的调制深度接近100%该2 pm超短脉冲激光器在生物医学和激光 通讯等领域具有非常重要的应用D关键词：Tm:LuAG陶瓷激光器；氧化石墨烯可饱和吸收体；调Q锁模；调制深度中图分类号：TN248.1 文献标志码：A DOI：10.3788/IRLA20190563Q-switched mode-locked all-solid-state Tm:LuAG ceramic laserChen Chen1,2,3,Xu Qiang1-3*,Sun Rui1,2,Zhang Ya'ni14.Kang Cuiping1.Zhang Mingxia2,Yuan Zhen2,Ling W eijun2(1. Institute of Physics and Optoelectronics Technology, Baoji University of Arts and Sciences, Baoji 721016, China;2. Institute of Laser Technology, Tianshui Nonna! University, Tianshui 741001, China;3. Baoji Engineering Technology Research Center on Ultrafast Laser and New Materials, Baoji 721016, China;4. School of Arts and Sciences, Shaanxi University of Science & Technology, Xi'an 710021, China)Abstract:Using graphene oxide (GO)by vertical growth m ethod as saturable absorber,an all-solid-state Q-switched m ode-locked Tm:L u3A15012 (Tm:LuAG)ceram ic laser with typical 'X'folded cavity was firstly dem onstrated.A790 n m laser diode(LD)was used as th e pum ping source.W hen th e pum ping power was greater th an8 W,th e laser en tered a stable Q-switched m ode-locked state.W hen th e ou tp u t m irror was5%, th e m axim um ou tp u t power of continuous light was714 mW,and th e oblique efficiency was4.94%. W hen th e pum ping power reached 16 W,th e m axim um ou tp u t power of th e laser was 200 mW,th e corresponding repetition frequency of m ode-locked pulse was 108.7 MHz,an d th e m odulation dep th of m ode locked pulse in Q-switched envelope was close to100%. The 2 ja m u ltrash ort pulsed laser h as im p ortan t applications in biom edicine and laser com m unication.收稿日期:2019-12-10;修订日期:2020-02-04基金项目:_家自然科学基金（11774257, 6丨564008, 11647008, 11504416);陕两省国际科技合作与交流计划项目（2021KW-39);宝鸡市重大科技专项计划项目（2015CXNL-1-3);天水市科技支撑计划自然科学基金项目（2018-FZ】HIC-3392);天水师范学院研究生创新引导项目（TYCX1901)第4期红外与激光工程第50卷Key words:Tm:LuAG ceram ic laser;graphene oxide saturable absorber;Q-switched m ode-locking;m odulation d ep th〇引言固体激光器的调Q锁模运转具有较高的峰值功 率和脉冲能量，已应用于生物医疗、材料微加工、表 面工程、太赫兹光学和激光雷达1121等重要领域。
Quantum_Dot
定义量子点(quantum dot)是准零维(quasi-zero-dimensional)的纳米材料，由少量的原子所构成。
粗略地说，量子点三个维度的尺寸都在100纳米(nm)以下，外观恰似一极小的点状物，其内部电子在各方向上的运动都受到局限，所以量子局限效应(quantum confinement effect)特别显著。
研究历史现代量子点技术要追溯到上世纪70年代中期，它是为了解决全球能源危机而发展起来的。
通过光电化学研究，开发出半导体与液体之间的结合面，以利用纳米晶体颗粒优良的体表面积比来产生能量。
初期研究始于上世体80年代早期2个实验室的科学家:贝尔实验室的Louis E.Brus博士和前苏联Yoffe研究所的AlexanderEfros和A.I.Ekimov博士。
Brus博士与同事发现不同大小的硫化镉颗粒可产生不同的颜色。
这个工作对了解量子限域效应很有帮助，该效应解释了量子点大小和颜色之间的相互关系，也同时也为量子点的应用铺平了道路。
1997年以来，随着量子点制备技术的不断提高，量子点己越来越可能应用于生物学研究。
1995年，AlivisatosI.Z.]和Nie两个研究小组首次将量子点作为生物荧光标记，并且应用于活细胞体系，他们解决了如何将量子点溶于水溶液，以及量子点如何通过表面的活性基团与生物大分子偶联的问题，由此掀起了量子点的研究热潮。
主要性质(1)量子点的荧光寿命长。
有机荧光染料的荧光寿命一般仅为几纳秒(这与很多生物样本的自发荧光衰减的时间相当）。
而量子点的荧光寿命可持续数十纳秒（20ns一50ns)，这使得当光激发后，大多数的自发荧光已经衰变子点荧光仍然存在，此时即可得到无背景干扰的荧光信号。
(2)生物相容性好。
量子点经过各种化学修饰之后，可以进行特异性连接，其细胞毒性低，对生物体危害小，可进行生物活体标记和检测。
(3)量子点具有很好的光稳定性。
量子点的荧光强度比最常用的有机荧光材料“罗丹明6G”高20倍，它的稳定性更是“罗丹明6G”的100倍以上。
激光锁模技术ppt课件
冲在腔内往返运动，每当此脉冲行进到输出反射镜时，便有一
个锁模脉冲输出。
➢脉冲宽度，即脉冲峰值与第一个光强为零的谷值间的时间间隔
sin[(2N 1) t ] 0但sin(t ) 0 t (m n )
2
2
2
2N 1
2 T 1
为锁模激光器的线宽
(2N 1) 2N 1
4.7.1 锁模原理
，
所以
(t1) (t1
2L) c
，以后这束光波每次通过调制器时损耗
相同。若损耗大于增益，这部分光波终将消失，而在损耗等于
零时通过的光每次都能无损耗的通过，会不断被放大，满足阈
值条件形成振荡，如果腔内损耗和增益控制得当，最终将形成
脉宽很窄，周期为T的脉冲序列输出。
损耗内调制锁模
➢从频率域模式耦合的角度来说明损耗调制锁模的原理。假设中心 频率 ν0 处的模首先振荡，其振幅调制后的电矢量为：
彼此独立的、随机的，所以总光场是各个模式光场的非相
干叠加。输出总光强是各个振荡模式光强之和，即 I Iq
输出光强随时间无规则起伏。
q
4.7.1 锁模原理
核心思想：锁模技术让谐振腔中存在的纵模同步振荡，让各模的频率 间隔保持相等并使各模的初位相保持为常数，激光器输出在时间上有 规则的等间隔的短脉冲序列。
实现锁模的方法
在一般激光器中，各纵模振荡互不相关，各纵模 相位没有确定的关系。并且，由于频率牵引效应， 相邻纵模的频率间隔并不严格相等。因此为了得到 锁模超短脉冲，须采取措施强制各纵模初位相保持 确定关系，并使相邻模频率间隔相等。
• 主动锁模 • 被动锁模 • 自锁模
4.7.2 主动锁模
在自由运转的激光器谐振腔中加入受外界信号控制的调制器， 对激光输出进行振幅或相位调制，实现各个纵模振动同步，叫 作主动锁模。 1. 振幅调制（损耗内调制锁模） ➢如图(4-31)所示，在谐振腔中插入一个电光或声光损耗调制器。 设调制周期为 Tm 2 Ω 2L c ，调制频率 νm c 2L (恰为纵 模频率间隔)
光纤激光器锁模原理介绍
光纤激光器锁模原理介绍Lasers are devices that produce intense beams of monochromatic light through the process of stimulated emission of radiation. Fiber lasers, in particular, are a type of solid-state laser that uses an optical fiber as the gain medium. Their ability to produce high-quality beams of light with high efficiency makes them highly desirable for a variety of applications, including cutting, welding, drilling, and marking in the industrial sector.激光是通过受激辐射过程产生强烈的单色光束的设备。
光纤激光器是一种将光纤作为增益介质的固体激光器。
它们能够高效地产生高质量的光束，因此在工业领域的切割、焊接、钻孔和标记等应用中备受青睐。
One fundamental principle behind the operation of fiber lasers lies in the process of mode locking. Mode locking refers to the synchronization of the phases of the modes of the laser’s electromagnetic field. By doing so, the laser produces pulses of light with a very narrow linewidth and high peak power, which is advantageous for many applications.光纤激光器运作背后的一个基本原理是锁模过程。
QuantumDots（量子点概述）
In terms of actual formation, the process characteristically went like this: ten atomic layers of film would form smoothly. As more layers were deposited, the film broke up into tiny pyramid-shaped islands. With more layers, the pyramids self-organized and coarsened, and then became dome-shaped islands.
optical and optoelectronic devices, quantum computing, and information storage.
Semiconductors with QDs as Material for Cascade Lasers
Semiconductors with QDs as Material for IR Photodetectors
The size ,shape and number of electrons can be precisely controlled
Just as in an atom, the energy levels are quantized due to the confinement of electrons.
These huge pressures, as new layers are deposited, force the initially flat film to separate into dots and then pop up into the third dimension to relieve stress, rather than continue to grow against resistance in two dimensions.
LED前沿技术:量子点(Quantum Dot)LED
LED前沿技术：量子点(Quantum Dot)LED李相敏【期刊名称】《科技信息》【年(卷),期】2010(000)021【摘要】LED技术以其高效、环保、节能在照明行业异军突起,然而LED最新的一项前沿技--量子点LED技术的出现将把LED的应用推向全新的高度.本文介绍了量子点LED的工作原理、技术优势、以及广间的应用前景和范围.【总页数】1页(P40)【作者】李相敏【作者单位】长江大学,湖北,荆州,434100【正文语种】中文【相关文献】1.The Electron-Hole Pair in a Single Quantum Dot and That in a Vertically Coupled Quantum Dot [J], XIE Wen-Fang;ZHU Wu2.Influences of a Side-Coupled Triple Quantum Dot on Kondo Transport Through a Quantum Dot [J], 江兆潭;杨彦楠;秦志杰3.The Electron－Hole Pair in a Single Quantum Dot and That in a Vertically Coupled Quantum Dot [J], XIEWen-Fang;ZHUWu4.SURFACE MORPHOLOGY OF SELF-ASSEMBLED VERTICALLY STACKED InAs QUANTUM DOTS BY SIZE-CONTROLLED GROWTH [J], S.W.Li;K.Koike5.High performance Ga N-based hybrid white micro-LEDs integrated withquantum-dots [J], Feifan Xu;Xu Cen;Bin Liu;Danbei Wang;Tao Tao;Ting Zhi;Qi Wang;Zili Xie;Yugang Zhou;Youdou Zheng;Rong Zhang因版权原因，仅展示原文概要，查看原文内容请购买。
量子点和量子点激光器
量子点的制造方法：量子点的制备可采用分子束外延技术在各种 自然表面上直接生长的方法。如在小偏角表面(vicinal surface) 超台阶面( super steps) 、高指数表面等或者在一些由人工做出 的图形衬底上生长。如V 形槽、在掩膜表面上选择局部生长、自 组织生长法等。下面介绍几种具体的制备方法
(1) 对于三维体系,在固体物理中,已求得其态 密度与能量的关系是抛物线形,如图(a) 所示。
(2)当体系为在某个方向(如z向)受限的二维体系(量子阱) 时，受限方向(z向)的平移对称性被破坏，kz不再是好量 子数，该方向发生能级分裂。一个本征态的能量可以写 为E=Ei + Exy（kx，ky），其中Ei是z方向的量子化的能级 值。 在量子阱中，电子能量
若要严格定义量子点，则必须由量子力学(quantum mechanics)出发。 我们知道电子具有粒子性与波动性，电 子的物质波特性取决于其费米波长(Fermi wavelength)
λF = 2π / kF
• 在一般块材中，电子的波长远小于块材尺寸，因此量子局限 效应不显着。
• 如果将某一个维度的尺寸缩到小于一个波长，此时电子只能 在另外两个维度所构成的二维空间中自由运动，这样的系统 我们称为量子阱(quantum well)；
对于零维的量子点而言，体系在x、y、z三个方向受限， 载流子的能量在三个方向上都是量子化的，不存在能量的 连续分布。所以，量子点的态密度与能量的关系表示为δ 函数的形式，即
ρ3D(E) = ∑ δ ( E - Ei)
i
其中Ei是体系的能量可取值，可表示为
量子点的能态图形为类氢光谱状的分离线， 如图(d)所示。
• 量子点是目前理论上与实验上的热门研究题 目，世界各国无不积极投入研究，主要领先 的有美国、日本、欧盟及俄罗斯等，台湾也 正在急起直追中。
1.6 μm波段锁模光纤激光器
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固体激光器与光纤激光器对光子晶体光纤棒耦合的分析与对比 Analysis and comparison of solid-state lasers and fiber lasers on the coupling of rod-type photonic crystal fiber 中国光学. 2018, 11(6): 958 https:///10.3788/CO.20181106.0958 20~1 250 Hz光纤激光加速度传感系统设计 20-1 250 Hz fiber laser acceleration sensing system 中国光学. 2017, 10(4): 469 https:///10.3788/CO.20171004.0469 结构紧凑的双波长连续波掺铒光纤激光器 Compact dual-wavelength continuous-wave Er-doped fiber laser 中国光学. 2019, 12(4): 810 https:///10.3788/CO.20191204.0810 不同角度包层光剥离的理论与实验研究 Stripping of cladding light at different angles: theoretical and experimental studies 中国光学. 2019, 12(5): 1124 https:///10.3788/CO.20191205.1124 国产化掺铥光纤激光振荡器性能研究 Investigation on the performance of a homemade thulium-doped fiber laser oscillator 中国光学. 2019, 12(5): 1109 https:///10.3788/CO.20191205.1109 负曲率空芯光纤对飞秒超短脉冲光的压缩研究 Femtosecond pulse compression using negative-curvature hollow-core fibers 中国光学. 2019, 12(1): 75 https:///10.3788/CO.20191201.0075
Quantum-Dot Light Emitting Diode and Packaging Met
专利名称：Quantum-Dot Light Emitting Diode andPackaging Method Thereof发明人：Chih-Jung Chen,Ray-Kuang Chiang申请号：US17376093申请日：20210714公开号：US20220025259A1公开日：20220127专利内容由知识产权出版社提供专利附图：摘要：A quantum-dot light emitting diode includes, in sequential order from bottom to top, a LED light source, a quantum-dot photoresist layer and a barrier layer. The quantum-dot photoresist layer has a thickness lower than 20 μm and is formed byspecific material, so as to decrease a step difference between the quantum-dot photoresist layer and a light exit surface of the LED light source, to improve coating property of the barrier material and make sure that the coating of the barrier material can be implemented by dry coating or wet coating; the barrier material is not easy to crack to cause air leakage and oxidation because of thermal expansion and contraction, so as to increase the success rate of side packaging and the reliability of the process, and extend the reliability of the material.申请人：Taiwan Nanocrystals Inc.地址：Tainan City TW国籍：TW更多信息请下载全文后查看。
锁模激光器
Mode-locked Lasers<<<| >>>|Feedback Definition: lasers which emit ult rashort pulses on t he basis of the technique of mode lockingA m ode-locked laser is a laser to which the technique of active or passive m ode lockingis applied, so that a periodic train of ul trashort pulses is em itted. See the article on m ode locking for m ore details on m ode-locking techniques; the present article focuses m ore on the lasers them selves. The article on ultrafast lasers also gives som e idea about current developm ents in ultrashort pulse generation.As ultrashort pulses have a certain bandwidth, m ode-locked lasers for short pulses (parti cularly in the sub-picosecond region) require a gain m edium with a large gain bandwidth. Other desirable features are a not too high nonlinearity and chrom ati c dispersion, and (particularly for passive m ode locking) high enough laser cross secti onsin order to avoid Q-switching instabilities.Types of Mode-locked LasersThe following types of lasers are attractive for m ode locking:∙In the 1970s, dye lasers were routinely used, which were pum ped wi th argon ion lasers. Laser dyes have a broad gain bandwidth, allowing for very short pulses.However, dye lasers have been largely replaced wi th solid-state lasers once these were able to deliver similar or better perform ance.∙Solid-statebulk lasers, based on ion-doped crystals or glasses, are today the dom inant type of m ode-locked lasers. They allow for very short pulses, very high pulse energies and/or average output powers, high or loss pulse repetition rates, and high pulse quality. Som e record achievem ents are listed below.Figure 1: Resonat or setup of a typical femtosecond mode-locked solid-st ate bulk laser with low or medium output power. The gain medium can be made of a crystal or of glass. A prism pair is used for dispersion compensation, and passive mode locking is achieved with a SESAM.∙Fiber lasers can also be m ode-lock ed for generating very short pulses with potentially cheap setups. See the arti cle on m ode-locked fiber lasers for m ore details.High output powers are typically not achieved directly, but by using fiber am plifiers.The achieved pulse durations of ultrafast fiber lasers are often limited by nonlinearities or by higher-order dispersion, rather than by the gain bandwidth.∙Sem iconductor lasers can be built as m ode-locked diode lasers, m ostly for applications in optical fiber comm unications. More recently, optically pum ped passively m ode-lock ed VECSELs have been dem onstrated which can rival other solid-state lasers, particularly if a com bination of relati vely high output power, a m ulti-gigahertz pulse repetition rate, and possibly a short pulse duration (a few picoseconds or less) is required.Design IssuesThe design of a m ode-locked laser is generally a non-trivial task, and particularly so if extrem e param eter regions for the pulse param eters are targeted. There is a com plicated interplay of m any effects, including dispersion and several nonlinear effects, and changing one design param eter often influences several others. (For exam ple, in a soliton m ode-locked laser a change in m ode size in the laser crystal or of the cavity length changes the balance of nonlinearity and dispersion, and thus also the pulse duration.) As a result, it can be diffi cult to achieve sim ultaneously very short pulses, stable operation, and a high power effi ciency. For given param eters of the gain m edium, there can be certain restrictions on the achievable pulse param eters. A relatively trivial one is that a gain m edium with a sm all gain bandwidth is not suitable for generating very short pulses. Certainly m ore surprising is e.g. the finding that m ode-locked solid-state lasers have difficulties in com bining a high pulse repeti tion rate with a high average output power, and that the additional requirem ent of generating sub-picosecond pulses m akes this trade-off even m uch m ore dem anding. Such const raints arise from a com bination of effects and issues such as Q-switched m ode locking and other kinds of instabilities, details of pulse shaping, and lim itations of saturable absorbers, and are also influenced by seem ingly totally unrelated issues such as the beam quality of the available pum p source.For such reasons, a very system ati c process of laser developm ent, based on a solid quantitative understanding of all the relevant physi cal details and on deep experience with typical lim itations, is essential for effi cient product developm ent. A key point is to work out a detailed laser design and to check quantitatively a num ber of issues before engaging in experim ental investigations. Without such preparations, there is a risk of getting into a com bination of problem s which can not sim ply be solved step by step.Some Special AchievementsSom e special achievem ents with passively m ode-lock ed solid-state lasers are:∙The very shortest pulses wi th durations below 10 fs (few-cycle pulses) are usually achieved with Kerr lens m ode locking of a Ti:sapphire laser [6, 5].∙High average output powers of up to ≈ 80 W in sub-pi cosecond pulses [14] and pulse energies above 10 μJ have been obtained from passively m ode-locked thin-disk lasers.∙Very high pulse repetition rates have been obtained wi th passively m ode-locked miniature bulk lasers [10, 15, 20] and also with harm onically m ode-locked fiber lasers. Even higher values of > 1 THz are possible with sm all laser diodes [4].∙Various kinds of lasers (norm ally wi th high pulse repeti tion rates) have reached quantum-lim ited timing jitter perform ance, thus outperform ing m any high-quality electronic oscillators.Figure 2: Miniature Er:Yb:glass laser setup for a pulse repetition rate of 50 GHz [15]. The cavit y length is only 3 mm (from the output coupler to t he SESAM). A modified setup allowed for even 100 GHz [20]. Higher Pulse Energies with Cavity DumpingAs explained in detail in the article on cavi ty dum ping, a m ode-locked laser can generate higher pulse energies of e.g. several m icrojoules at lower pulse repetition rates (e.g. 100 kHz or 1 MHz) by incorporation of a cavity dumper in the laser resonator. The basi c principle is to form a high-energy pulse wi thin the resonator while having low resonator losses, and then to couple out of the energy with the cavi ty dum per.Typical Applications of Mode-locked LasersThe following list gives som e im pression of the m anifold appli cations of m ode-locked lasers:∙The high pulse intensities are used for applications in m aterial processing, such as m icrom achining, surface treatm ent, drilling holes, and three-dim ensional laser prototyping.∙In the m edical dom ain, mode-lock ed lasers m ay again be used for a kind of m aterial processing, e.g. as a laser scalpel or in ophthalm ology. However, there are also photochem ical effects used e.g. for certain skin treatm ents, and im portant applications in im aging.∙Various m ethods of im aging, m icroscopy and spectroscopy, as applied in different dom ains, greatly profit from short pulses for various reasons.∙Short pulses allow for tim e-resolved m easurem ents, e.g. electro-optic sam pling m easurem ents on integrated electroni c circuits, or pum p–probe m easurem ents on sem iconductor devices such as SESAMs.∙In the field of m etrology, m ode-locked lasers can be used for distance m easurem ents, but also in frequency m etrology (tim e keeping) and other fields.∙ A num ber of processes for nonlinear frequency conversion are greatly facilitated by the high peak powers of m ode-lock ed lasers, and are im portant e.g. for laser projection displays.∙Other fields with a large potential are m icrowave, m illim eter-wave and terahertz opti cs, and picosecond optoelectroni cs.。
量子点激光器
• 量子点的用途相当广泛，例如：可用于蓝光 量子点的用途相当广泛，例如： 雷射、光感测元件、单电子电晶体(single 雷射、光感测元件、单电子电晶体 electron transistor, SET)、记忆储存、触 、记忆储存、 媒以及量子计算(quantum computing)等， 媒以及量子计算 等 在医疗上更利用各种发光波长不同的量子点 制成萤光标签，成为生物检测用的「 制成萤光标签，成为生物检测用的「纳米条 码」。 • 量子点是目前理论上与实验上的热门研究题 世界各国无不积极投入研究， 目，世界各国无不积极投入研究，主要领先 的有美国、日本、欧盟及俄罗斯等， 的有美国、日本、欧盟及俄罗斯等，台湾也 正在急起直追中。 正在急起直追中。
在GaAs基材上以自组成法生 长 InAs量子点的STM影像(取自Ref.2)
3.微影蚀刻法 微影蚀刻法 (lithography and etching)： ： 以光束或电 子束直接在 基材上蚀刻 制作出所要 之图案， 之图案，由 于相当费时 因而无法大 量生产。 量生产。
基材蚀刻窄圆柱式量子点<br> 之SEM影像，水 影像， 以GaAs基材蚀刻窄圆柱式量子点 基材蚀刻窄圆柱式量子点 影像 平线条约0.5微米 平线条约 微米
1997年 Maximov等将量子点置入 2. 1997年，Maximov等将量子点置入 GaAs/AlGaAs量子阱中 量子阱中， GaAs/AlGaAs量子阱中，使量子点中载流子的 逸出势垒高度增加， 逸出势垒高度增加，大大降低了载流子的逸 出几率，减小了漏电流， 出几率，减小了漏电流，使激光器的特征温 在工作温度80K 330K之间高达385K， 80K之间高达385K 度T0在工作温度80K-330K之间高达385K，远远 高于量子阱激光器的特征温度，但提高T 高于量子阱激光器的特征温度，但提高T0的同 时却带来了阈值电流密度的大幅提升。 时却带来了阈值电流密度的大幅提升。1999 Shernyakov报道了世界上第一只在室温 年Shernyakov报道了世界上第一只在室温 低于40℃ 下同时具有高特征温度T (160K） 40℃） （低于40℃）下同时具有高特征温度T0 (160K） 和低阈值电流密度J 和低阈值电流密度Jth=65A/cm2 ，三层量子点 阵列的GaAs基量子点激光器，工作波长为 阵列的GaAs基量子点激光器， GaAs基量子点激光器 1.3μm。而目前工作在同波段的InP InP基量子阱 1.3μm。而目前工作在同波段的InP基量子阱 激光器，最高的特征温度T0 60T0为 激光器，最高的特征温度T0为60-70K ，最低 的阈值电流密度J 300的阈值电流密度Jth为300-400A/cm2。
第7章讲义时间分辩光谱_766107711
一个调Q 开关激光的泵浦功率P P (t), 振荡阈值，反转密度出功率P L (t)的示意图Such an optical switch can be realized, for instance, if one of the resonatormirrors is mounted on a rapidly spinning motor shaft. Only at that time t0 where the surface normal of the mirror coincides with the resonator axis is the incident light reflected back into the resonator, giving a high Q value of the laser cavity. The optimum time t0 can be selected by imaging the beam of a light-emitting diode (LED)after reflection at the spin motor onto the detector D , which provides the trigger signal for the flash lamp of the Q-switch laser.用快速转动的反射镜当Q －开关在激光腔内放入一个Pockel-cell 和两个相互垂直的偏振器当Q －开关。
Pockel-cell 有一块各向异性晶体，在电场下能旋转光的偏振方向。
锁模激光(Mode-Luck Lasers)当激光腔内没有选频元件时，激光腔内同时有多模振荡，模之间无位相关系。
如果用一个光调制器把所有同时振荡的模的位相耦合起来，这些模的振幅相干叠加出的激光会是ps 超短脉冲。
这种模的耦合又叫锁模，产生的激光叫锁模激光。
主动锁模示意图. 如图，把一个调制器放入激光腔内。
超短脉冲“8”字形被动锁模掺铒光纤激光器
超短脉冲“8”字形被动锁模掺铒光纤激光器陈志宇;唐志杰;桑明煌【期刊名称】《江西师范大学学报（自然科学版）》【年(卷),期】2012(036)002【摘要】The experimental study of Erbium doped fiber lasers using the nonlinear amplifying loop mirror for mode-locked operating is reported, we optimize dispersion management in the cavity. The fiber figure-8 erbium doped laser can realize self-starting passively mode-locked and directly produce 1.77×l0‐13 s ultrashort pulses output in 1 550 nm wavelengths. The average output power was 12 mW under a 300 mW pump power with a repe-tition rate of 19.7 MHz. The laser is operated simply because of all-fiber construction in the cavity. It can steady work hours in optical platform under the mode-locking condition.%利用非线性放大环形镜被动锁模方法对锁模光纤激光器进行实验研究,引入色散管理方法,实现了“8”字形掺铒光纤激光器的自启动被动锁模,在1550 nm波段上得到了光谱宽度16 nm、脉宽为1.77×10-13 s的超短脉冲输出.泵浦功率在300 mW时,激光器实现了重复频率为19.7 MHz,平均输出功率12 mW的锁模脉冲输出.整个激光腔为全光纤结构,而且操作简单,锁模输出状态下的激光器可以在光学平台上稳定运行数小时.【总页数】4页(P124-126，154)【作者】陈志宇;唐志杰;桑明煌【作者单位】江西师范大学物理与通信电子学院,江西南昌330022;江西师范大学物理与通信电子学院,江西南昌330022;江西师范大学物理与通信电子学院,江西南昌330022【正文语种】中文【中图分类】TN248【相关文献】1.被动锁模掺铒光纤激光器中的有理数谐波锁模 [J], 况庆强;桑明煌;聂义友;张祖兴2.基于饱和吸收镜的被动锁模掺铒光纤激光器 [J], 欧攀;贾豫东;林志立;刘磊3.被动锁模掺铒光纤激光器自相似脉冲的啁啾提取 [J], 吴戈; 田小建; 高博; 单江东4.被动锁模掺铒光纤激光器自相似脉冲的啁啾提取(英文) [J],5.MnPS3可饱和吸收体被动锁模掺铒光纤激光器双波长激光 [J], 俞强;郭琨;陈捷;王涛;汪进;史鑫尧;吴坚;张凯;周朴因版权原因，仅展示原文概要，查看原文内容请购买。
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m* N (Байду номын сангаас) 2 Lz
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Broadband high gain amplification
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Loss decreases with optical intensity
Subpicosecond pulses directly from a QD laser
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Performance of QDMLLs
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Applications & challenges
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Mode-locking techniques
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Three main forms of mode-locking
Direct modulation of the gain section with a frequency equal to the repetition frequency of the cavity.
Optical communication systems
A
Optical clocks for computer motherboards Biophotonics applications
Deploying a higher number of QD layers in the active region Using colliding-pulse mode-locking
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Ultrafast carrier dynamics — QD lasers
• Requiring low current to initiate lasing • Insensitive to temperature changes • Routinely grown on GaAs substrates • Strongly suppressed carrier diffusion • Exploiting GS and ES bands
Application: QD-SOA • Small size • High gain (> 18 dB) • Ultrashort pulses • Broad spectral range • High repetition rates (distortion-free)
[1]Rafailov E U, Loza-Alvarez P, Sibbett W, et al. Amplification of femtosecond pulses over by 18 dB in a quantum-dot semiconductor optical amplifier[J]. Photonics Technology Letters IEEE, 2003, 15(8):1023-1025. [2]Rafailov E U, Cataluna M A, Sibbett W. Mode-locked quantum-dot lasers[J]. Nature Photonics, 2007, 1(1):395-401.
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High repetition rates
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Thank you!
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Mode-locked quantum-dot lasers
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Outline
Introduction of quantum dots Application of quantum dots Introduction of mode-locking Passive mode-locking lasers Performance of QDMLLs Applications of QDMLLs
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Quantum confinement
Step-like density of states
2 2 2 2l 2 2 k x2 k y El * 2m* L2 2 m 2m* z
Spiked decaying density of states
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Delta function density of states
El ,m ,n 2 2l 2 2 2 m 2 2 2 n 2 * 2 * 2 2m* L2 2 m L 2 m Ly z x 2 Lx L y Lz
Using a saturable absorber incorporated into the laser, and providing the shortest pulses of all three techniques. Pulse generation is driven by an RF current imposed on the gain or absorber section, whereas further shaping and shortening is assisted by a saturable absorber.
• Broadband high gain amplification • Ultrafast carrier dynamics
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Quantum dots
• Zero-dimensional; • Nanoparticles/structures, size: ~2-10nm • Composed of groups II-VI, III-V, and IV-VI materials
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Passive mode-locking of lasers diodes
• A saturable absorber is incorporated into the laser cavity • In practical terms, it can be monolithically integrated into a semiconductor laser, by electrically isolating one section of the device