Wideband synchronization of two quantum dot mode-locked laser frequency combs using optical injection

Abstract

We experimentally investigate the unidirectional coupling between two semiconductor frequency combs generated by two passively mode-locked quantum dot lasers. We show that synchronization of the combs in terms of repetition rate and phase locking is possible for a wide range of detuning between the combs. Repetition rate locking of the combs leading to reduced phase noise operation for the slave comb can occur independently of phase locking. Furthermore, we study the synchronization with respect to specific features of the two lasers, such as the optical bandwidth, the peak wavelength mismatch, and the injected power levels.