240 GHz pedestal-free colliding-pulse mode-locked laser with a wide operation range

Abstract

A 240 GHz, sixth-harmonic monolithic ~1.55 m colliding-pulse mode-locked laser is reported using a three-quantum-well active layer design and a passive far-field reduction layer. The device emits 0.88 ps pulses with a peak power of 65 mW and intermediate longitudinal modes suppressed by >30 dB. The device demonstrates a wide operation range compared to the conventional five-quantum-well design as well as having a low divergence angle (12.7 26.3), granting a twofold improvement in butt-coupling efficiency into a flat cleaved single-mode fibre.