Page 388 - Fiber Bragg Gratings

8.2 Static and dynamic properties of FGLs 365

shown to have extremely good thermal behavior, with the elimination of
mode hops. The L-I characteristic at different temperatures shows kink-
free operation over a wide temperature range, and the laser is therefore
suitable for WDM applications. Figure 8.8 demonstrates the excellent cou-
pling (high output power) and the smooth light output curves [30].
As a wavelength selector for a laser, the fiber Bragg grating offers a
unique solution. The broad-gain bandwidth of semiconductor lasers com-
bined with the quality of single-mode fiber connectors resulted in a "wave-
length-uncommitted" laser [26]. A schematic of this device is shown in Fig.
8.9. The basic device consists of an AR-coated laser chip with a short fiber
pigtail terminated in a fiber connector. Fiber Bragg gratings at various
wavelengths, also packaged in fiber-FC-PC connectors, are then used to
define the operating wavelength of the laser. A set of gratings allows a large

Figure 8.9: Wavelength-uncommitted laser [26].

Figure 8.10: SMSR of -50 dB for a fiber grating semiconductor laser with
an output power of ~2 mW.