Generation of ultra-high repetition rate optical pulses through external injection in passively mode-locked monolithical semiconductor lasers

摘要

A wide number of applications, such as THz signal generation, ultrafast optical clocking and next generation optical communication systems require high repetition rate optical pulses. Passively mode-locked semiconductor lasers using saturable absorbers (SAs) in a Fabry-Pérot configuration are excellent candidates, providing high-quality pulse trains in a very compact device [1]. The technical difficulties of cleaving edge-emitting lasers shorter than a few hundreds of microns limit their fundamental cavity repetition rate to tens of GHz. Colliding Pulse Mode-Locking (CPM, [2]) or Compound Cavity Mode-Locking (CCM, [3]) have been proposed as a way to increase the repetition rate of passively mode-locked semiconductor lasers: both rely on lithographically defined sub-cavities, therefore despite high achievable repetition rates their tunability is limited.