Title :
Low-chirp and external optical feedback resistant characteristics in λ/8 phase-shifted distributed-feedback laser diodes under direct modulation
Author :
Huang, Yidong ; Sato, Kenji ; Okuda, Tetsuro ; Suzuki, Naofumi ; Ae, Satoshi ; Muroya, Yoshiharu ; Mori, Kazuo ; Sasaki, Tatsuya ; Kobayashi, Kenichi
Author_Institution :
Photonic & Wireless Devices Res. Labs., NEC Corp., Shiga, Japan
fDate :
11/1/2002 12:00:00 AM
Abstract :
Clarifies that phase shift value in directly modulated distributed feedback laser diodes (DFB-LDs) affects their chirp characteristics and resistance to external optical feedback because of the feedback effect of mirror loss (FEML). Comparing λ/8, λ/4, and 3/λ8 phase-shifted DFB-LDs, theoretically and experimentally, showed that the negative FEML in λ/8 phase-shifted DFB-LDs improves their transmission performance and makes them more resistant to external optical feedback. It was demonstrated with 2.5-Gb/s directly modulated 1.55-μm λ/8 phase-shifted DFB-LDs that a very low-power penalty for 100-km transmissions (less than 1 dB for BER=10-10) can be obtained within a wide extinction ratio from 8.5 to 14.5 dB. Excellent resistance to optical feedback was also demonstrated using λ/8 phase-shifted DFB-LDs: isolator-free 80-km transmission was successful under -14-dB external optical feedback. In addition, the relation of transmission characteristics to coupling coefficient κL and detuning between oscillation wavelength and gain maximum was also discussed here for designing low chirp λ/8 phase-shifted DFB-LDs.
Keywords :
chirp modulation; distributed feedback lasers; electro-optical modulation; error statistics; laser feedback; laser mirrors; optical phase shifters; optical transmitters; quantum well lasers; λ/8 phase-shifted distributed-feedback laser diodes; 1.55 micron; 100 km; 2.5 Gbit/s; 80 km; BER; chirp characteristics; coupling coefficient; detuning; direct modulation; directly modulated DFB-LD; external optical feedback resistant characteristics; feedback effect of mirror loss; gain maximum; isolator-free 80-km transmission; low-chirp; metropolitan area networks; negative FEML; oscillation wavelength; transmission performance; very low-power penalty; wide extinction ratio; Chirp modulation; Couplings; Diode lasers; Distributed feedback devices; Extinction ratio; Laser feedback; Mirrors; Optical feedback; Optical losses; Phase modulation;
Journal_Title :
Quantum Electronics, IEEE Journal of
DOI :
10.1109/JQE.2002.804292
