Monolithic colliding pulse mode-locked semiconductor lasers

Abstract

In this paper we investigate the temporal and spectral properties of monolithic colliding pulse mode-locked (CPM) quantum-well lasers. A large-signal model for the CPM laser is derived, which explains the mode-locking behaviour of both passively and hybridly mode-locked CPM lasers. The pulse-shaping and wavelength chirp of the CPM pulses are found to be the result of a complicated interplay between the gain and saturable absorber dynamics. The experimentally measured pulse width dependence upon variation of gain current and applied reverse bias on the saturable absorber is explained by fast gain dynamics. The experimentally observed broadening of the optical power spectrum with gain current is found mainly to be due to the self-phase modulation in the gain sections.