Stabilization and Timing Jitter Reduction of 160 GHz Colliding-Pulse Mode-Locked Laser Diode by Subharmonic-Frequency Optical Pulse Injection

Shin ARAHIRA  Yukio KATOH  Daisuke KUNIMATSU  Yoh OGAWA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E83-C   No.6   pp.966-973
Publication Date: 2000/06/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Advanced Optical Devices for Next Generation High-Speed Communication Systems and Photonic Networks)
Category: High-Speed Optical Devices
Keyword: 
mode-locked laser diode,  stabilization,  timing jitter,  down converting,  

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Summary: 
A 160 GHz colliding-pulse mode-locked laser diode (CPM-LD) was stabilized by injection of a stable master laser pulse train repeated at a 16th-subharmonic-frequency (9.873 GHz) of the CPM-LD's mode-locking frequency. Synchroscan steak camera measurements revealed a clear pulse train with 16-times repetition frequency of the master laser pulse train for the stabilized CPM-LD output, indicating that CPM-LD output was synchronized to the master laser and that the timing jitter was also reduced. The timing jitter of the stabilized CPM-LD was quantitatively evaluated by an all-optical down converting technique using the nonlinearity of optical fiber. This technique is simple and has a wider bandwidth in comparison to a conventional technique, making it possible to accurately measure the phase noise of ultrafast optical pulse train when its repetition frequency exceeds 100 GHz. The electrical power spectra measurements indicated that the CPM-LD's mode-locking frequency was exactly locked by the injection of the master laser pulse train and that the timing jitter decreased as the injection power increased. The timing jitter was reduced from 2.2 ps in free running operation to 0.26 ps at an injection power of 57 mW, comparable to that of the master laser (0.21 ps).