Experimental investigation of relaxation oscillations resonance in mode-locked Fabry-Perot semiconductor lasers

TL;DR

This paper experimentally investigates the behavior of relaxation oscillations in a mode-locked semiconductor laser diode, revealing coexisting regimes of self-pulsations and resonance at specific optical modulation frequencies.

Contribution

It provides the first detailed experimental analysis of relaxation oscillation resonance in a mode-locked Fabry-Perot semiconductor laser without saturable absorber.

Findings

Identification of resonance of relaxation oscillations at specific regimes

Observation of coexisting self-pulsations and mode-locking regimes

Characterization of output modulation at 40 GHz FSR

Abstract

We propose in this communication an experimental study of the relaxation oscillations behavior in mode-locked lasers. The semiconductor self-pulsating laser diode is composed by two gain sections, without saturable absorber. It is made of bulk structure and designed for optical telecommunication applications. This specific device allows two different regimes of optical modulation: the first one corresponds to the resonance of the relaxation oscillations and the second one, to the mode-locking regime at FSR value. This singular behavior leads us to characterize the self-pulsations which are coexisting in the laser and to describe two regimes of output modulation: the first one appears thanks to the resonance of the oscillation relaxation and the other one corresponds to the FSR of the Fabry-Perot laser at 40 GHz.