Title :
Fast spectral improvement in picosecond pulses generated from a DFB laser diode using a loosely coupled external cavity
Author :
Chow, K.K. ; Shu, C.
Author_Institution :
Dept. of Electron. Eng., Chinese Univ. of Hong Kong, Shatin, China
fDate :
4/1/2001 12:00:00 AM
Abstract :
A simple external cavity is constructed to provide adjustable feedback to a gain-switched distributed feedback laser diode. A 27-dB enhancement in the sidemode suppression ratio (SMSR) and a 0.3-nm reduction in the spectral linewidth have been observed. The improvement shows a saturation behavior when the feedback power reaches about -16 dBm. We report on the evolution and the dynamics of the spectral improvement. The steady state can be achieved as soon as four round-trip feedback cycles are completed. Dependences of the speed of improvement and the SMSR on the feedback pulse arrival time are also investigated. The optimal result can be obtained over a sensitive time window of about 20 ps.
Keywords :
distributed feedback lasers; laser cavity resonators; laser feedback; laser modes; optical pulse generation; optical transmitters; time division multiplexing; 20 ps; DFB laser diode; adjustable feedback; fast spectral improvement; feedback power; feedback pulse arrival time; gain-switched distributed feedback laser diode; loosely coupled external cavity; optimal result; picosecond pulse generation; round-trip feedback cycles; saturation behavior; sensitive time window; sidemode suppression ratio; simple external cavity; spectral improvement; spectral linewidth; Diode lasers; Distributed feedback devices; Laser feedback; Optical attenuators; Optical coupling; Optical feedback; Optical fiber polarization; Optical pulse generation; Optical pulses; Stimulated emission;
Journal_Title :
Photonics Technology Letters, IEEE
