Dynamics of Mode-Locked InP Based Quantum Dash Lasers for Optical Communications

In this paper, we demonstrate experimental results on dynamics of mode-locked quantum dash lasers. First, we show short pulse (ps) generation from single-section self-mode-locked lasers by filtering the optical spectrum and directly from two-section saturable-absorber mode-locked lasers. Second, we demonstrate narrow linewidth, frequency-tunable microwave generation using CW injection locking of self-mode-locked quantum dash lasers. Keywords: Injection-locked oscillators, quantum dash lasers, mode-locked lasers, microwave oscillators. 1. INTRODUCTION Semiconductor mode-locked lasers have shown promising performance as compact and reliable sources for ultra-short pulse generation with low timing jitter and with diverse applications in optical communications, metrology, optical sampling, and remote sensing [1]. Mode-locked diode lasers based on quantum-dot emitting at 1.3 µm are strong candidates for pulse sources among their quantum well and bulk counterparts, because of their fast carrier dynamics, wide optical gain, and high stability [2-4]. At 1.5 µm wavelength, single-section quantum dash lasers have shown high repetition rate mode-locked behaviour with very low timing jitter [5, 6]. These devices have shown successful performance in optical communication systems such as optical clock recovery [7] and WDM transmission [8]. While short pulse generation was also reported directly from 245 GHz single-section lasers [6], because of change of the static phase for the longitudinal modes of the laser, pulse compression techniques are needed to generate short pulses from these lasers [9, 10].