Passively mode-locked 1 GHz MOPA system generating sub-500-fs pulses after external compression

Abstract

We compared the performance of DQW and TQW edge-emitters in a passively mode-locked 1 GHz MOPA system at 1075 nm wavelength. Passive mode-locking is induced by applying a reverse DC voltage to the absorber section. The average power is increased up to 0.9 W by a single-stripe pre-amplifier and a tapered amplifier. After compensation of the quadratic chirp in a grating compressor we achieved a pulse duration of 342 fs. We found that the oscillator gain current and the absorber bias voltage have significant impact on the pulse duration. Both parameters were used to optimize the MOPA system with respect to the shortest pulse length after compression.