光电子学与光子学的原理及应用s.o.kasa chapter4课后答案

same, energy transfer from excited He atoms to Ne atoms by atomic collisions in the gas discharge tube. There are two excited states for the He atom in the configuration 1s12s2. The configuration with electron
b The human eye is at least twice as sensitive to orange color light than for the red. Discuss typical applications where it is more desirable to use the orange laser.
spins parallel has a lower energy than that with opposite electron spins as indicated in Figure 4Q1. These
two He states can excite Ne atoms to either the 2p54s1 or 2p55s1. There is then a population inversion between these levels and the 2p53p1 and between 2p55s1 and 2p54p1 which leads to the above lasing
543.5
594.1
Green
Yellow
Optical output power (mW) 1.5
2
Typical current (mA)
6.5
6.5
Typical voltage
2750
2070
612 Orange 4 6.5 2070
632.8 Red 5 6.5 1910
1523 Infrared 1 6 3380
transitions. Generally, we do not have a single discrete level for the energy of a many-electron atom of
given n,l configuration. For example, the atomic configuration 2p53p1 has 10 closely spaced energy
cFra Baidu bibliotek
The 1523 nm emission has potential for use in optical communications by modulating the laser
beam externally . By considering the spectral line width (∆υ ≈ 1400 MHz), typical powers, stability,
(le3vpe1)lsarnedsuthlteinrgemfraoimninvgareioleucstrdoinffse(r2enp5t)vwaliutheisnoqfumanl atunmd mmsetchhaat nciacnalarsusilgesn.edNtoot
the all
sixth excited transitions to
(543.5 nm), orange (612 nm), yellow (594.1 nm), and in the infrared regions at 1.52 µm and 3.39 µm,
which give the He-Ne laser its versatility. The pumping mechanism for all these lasers operations is the
electron these
energy levels are allowed as photon emission requires quantum number selection rules to be obeyed.
a Table 4Q1, shows some typical commercial He-Ne laser characteristics (within 30-50%) for various wavelengths. Calculate the overall efficiencies of these lasers.
Solutions Manual for Optoelectronics and Photonics: Principles and Practices S.O. Kasap
4.1
15 April 2002
Chapter 4
4 . 1 The He-Ne Laser The He-Ne laser system energy levels can be quite complicated as shown in Figure 4Q1. There are a number of lasing emissions in the laser output in the red (632.8 nm), green
Solutions Manual for Optoelectronics and Photonics: Principles and Practices S.O. Kasap
4.2
15 April 2002
He (1s12s1)
20.6 eV Collisions
(1s12s1)
19.8 eV
discuss the advantages and disadvantages of using a He-Ne laser over a semiconductor diode.
Table 4Q1
Typical commercial He-Ne laser characteristics
Wavelength (nm)