Pulse train stability in high-bit-rate frequency-modulated Er-Yb laser transmitters

Summary form only given. The achievement of a stable optical pulse source in the 1.5 /spl mu/m wavelength region with a high repetition rate is extremely important for its use as a transmitter in soliton-based optical transmission systems. In recent work, we proposed and demonstrated a novel non-resonant technique for the generation of high-bit-rate transform-limited pulse trains, based on asynchronous FM of an Er-Yb laser with external spectral filtering by a Bragg fiber grating. This technique enables to relax the strict constraint of cavity length control needed with conventional active mode-locking methods. In this work we present a comparative analysis of pulse train stability based on BER measurements, of a 2.5-GHz frequency-modulated Er-Yb laser operated in FM mode-locking (synchronous modulation) and in the FM regime (asynchronous modulation), and demonstrate the significant lower sensitivity to cavity length detuning of the latter configuration as compared to standard mode-locking.