Page 378 - Fiber Bragg Gratings

Chapter 8

Fiber Grating Lasers and

Amplifiers

The arrival of the in-fiber Bragg grating could not have been at a better
time for rare-earth-doped fiber. Research and development in the field
of doped fibers was at such a stage that fiber amplifiers were already
commercially available; thus, fiber Bragg gratings were a natural progres-
sion for combining the attributes of the fibers and amplifiers, as well as
semiconductor devices. Their success in this area are due to the near-
perfect reflection characteristics of the grating and the ultralow insertion
loss, as well as the ease with which they can be tailored for a particular
application. One of the most attractive features of the in-fiber Bragg
grating is its transparency to wavelengths outside of the band stop. Apart
from becoming integral components of narrow-band lasers, the side-tap
filter and the long-period grating have also been particularly useful for
equalizing the gain of optical fiber amplifiers. This chapter introduces
some of the applications of fiber gratings in narrow-band, low-chirp lasers
and mode-locked, short-pulse sources, as well as in tailoring the gain and
stability of amplifiers.

8.1 Fiber grating semiconductor lasers:
The FGSL

Semiconductor laser diode technology has been refined to produce low-
threshold, high-power and narrow-linewidth devices (distributed feedback

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