Page 169 - Photonics Essentials an introduction with experiments
P. 169
Lasers
Lasers 163
Gain spectrum
Frequency
Cavity reflectivity
f =
c
2Ln
Frequency
Reflectivity + gain
Frequency
Figure 7.10. The resonant wavelengths of a laser cavity are those select wavelengths
for which a standing wave can be established between the two mirrors at either end of
the cavity. The special wavelengths are called modes and are equally spaced in fre-
quency. There are many such modes. Only the few that happen to occur in the gain
spectrum of the semiconductor material will participate in the necessary positive pho-
ton feedback.
Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.
