Characteristic Analysis and Pulse Compression of theeak-Resonat-Cavity Fabry-Perot Laser Diode Mode-Lockediber Ring
Date Issued
2008
Date
2008
Author(s)
Peng, Guo-Hsuan
Abstract
In this thesis, we discussed the characteristics of optical injection mode-locking of a weak-resonant-cavity Fabry-Perot laser diode based fiber ring. The 10 GHz mode-locking pulse was generated by using the 10 GHz dark-optical comb injection. The thesis has three mainly parts: irst, the optical injection mode-locking of a weak-resonant-cavity Fabry-Perot laser diode based fiber ring with an intra-cavity power controlled wavelength shift and a reducing chirp linewidth at high intra-cavity coupling ratio condition is demonstrated. Both the strong dark-optical comb and strong feedback coupling contribute to the wavelength spectrum shift toward longer wavelength, a wavelength shift from 1536 to 1542 nm of the weak-resonant-cavity FPLD based fiber ring associated with its pulsewidth and linewidth also reduced from 27 to 19 ps and from 10 to 6 nm, respectively, can be observed. Furthermore, the peak-to-peak frequency chirp reduced from 3.5 to 1.8 GHz was caused by the shrink of linewidth. Second, a novel optical TDM pulsed carrier from optically injection-mode-locked weak-resonant-cavity Fabry-Perot laser diode (FPLD) with 10%-end-facet reflectivity is demonstrated with tunable mode spacing matching ITU-T DWDM channels. The FPLD exhibits relatively weak cavity modes and a gain profile covering > 33.5 nm with intracavity mode spacing of 1.6 nm. The mode-spacing spacing was tunable by adjusting length of the fiber ring cavity. The least multiple between the longitudinal modes of ring cavity and FPLD result in 12 lasing modes with channel spacing of 200 GHz and a mode-locking pulsewidth up to 19 ps. The operating wavelength can further extend from 1520 to 1553.5 nm. After channel filtering, each selected longitudinal mode component give rises to shortened pulsewidth of 12 ps due to reduced group velocity dispersion. By linear dispersion compensating with 55 m long dispersion compensation fiber (DCF), the pulsewidth can be further compressed to 8.5 ps with corresponding chirp reducing from 9.7 to 4.3 GHz. Final, 1.4-picosecond nonlinear pulse compression of a backward dark-optical-comb injection harmonic-mode-locked semiconductor optical amplifier based fiber laser (SOAFL) is demonstrated. With the tunable bandpass filter (TBF) in the fiber ring, shortest mode-locked SOAFL pulsewidth of 12 ps at 10 GHz is generated, which can further be compressed to 1.4 ps after nonlinear soliton compression. A maximum pulsewidth compression ratio for the compressed fifth-order mode-locked SOAFL is reported. The fifth-order soliton can be obtained by injecting the amplified pulse with peak power of 10.8 W into a 400m-long single-mode fiber (SMF). The tolerance in SMF length is relatively large (400-700 m) for obtaining <2 ps mode-locked SOAFL pulsewidth. However, without the TBF in fiber ring, the mode-locked SOAFL linewidth can be broadened to 2.4 nm and the pulsewidth were broaden to 21 ps. It can be linear compensated to 12 ps by passing through the 70m-long dispersion compensation fiber (DCF). It can be further compressed to 2.1 ps after fifth-order soliton compression, at the same time, the linewidth of mode-locked SOAFL broadened from 2.4 to 3.8 nm.
Subjects
weak-resonant-cavity Fabry-Perot laser diode
dark-optical comb
frequency chirp
dispersion compensation
nonlinear soliton compression effect.
Type
thesis
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