ABSTRACT
This research carries out coherence measurements of a 42.7 GHz quantum dash (QDash) semiconductor laser when passively, electrically, and optically mode-locked. Coherence of the spectral lines from the mode-locked laser is determined by examining the radio frequency beat-tone linewidth as the mode spacing is increased up to 1.1 THz. Electric-field measurements of the QDash laser are also presented, from which a comparison between experimental results and accepted theory for coherence in passively mode-locked lasers has been performed.
ABSTRACT
The application of a mode-locked quantum-dot Fabry-Perot (QD-FP) laser in a wavelength preserving all-optical 3R regenerator is demonstrated at 40 Gb/s. The 3R regenerator consists of a QD-FP laser for low-timing jitter clock recovery, cross-phase modulation based retiming, and self-phase modulation based reshaping. The performance of the alloptical 3R regenerator is assessed experimentally in terms of the Q-factor, timing jitter and bit-error ratio.
ABSTRACT
We investigate experimentally all-optical clock recovery for return-to-zero (RZ) and nonreturn-to-zero (NRZ) differential phase-shift keying (DPSK) signals at 40 Gbits/s using a passively mode-locked quantum-dot Fabry-Perot (QD-FP) semiconductor laser. The QD-FP laser exhibits a beat spectrum linewidth of 80 kHz, which enables a recovered clock signal with a root-mean-square timing jitter of 160 fs for the RZ-DPSK signal and 240 fs for the NRZ-DPSK signal. The timing jitter of the recovered clock signal is characterized for different values of the input signal power and the input signal optical signal-to-noise ratio.
