Self-generation of optical frequency comb in single section Quantum Dot Fabry-Perot lasers: a theoretical study

TL;DR

This theoretical study explains how single-section Quantum Dot Fabry-Perot lasers can spontaneously generate optical frequency combs through multi-mode dynamics and nonlinear interactions, aligning well with recent experimental findings.

Contribution

The paper provides a detailed physical understanding of OFC generation in QD lasers using a comprehensive TDTW model that includes coherent interactions and carrier gratings.

Findings

Multi-mode spectrum arises just above threshold due to carrier gratings.

Self-mode-locking and OFC emission occur at higher bias currents.

Results agree closely with recent experimental observations.

Abstract

Optical Frequency Comb (OFC) generated by semiconductor lasers are currently widely used in the extremely timely field of high capacity optical interconnects and high precision spectroscopy. Very recently, several experimental evidences of spontaneous OFC generation have been reported in single section Quantum Dot (QD) lasers. Here we provide a physical understanding of these self-organization phenomena by simulating the multi-mode dynamics of a single section Fabry-Perot (FP) QD laser using a Time-Domain Traveling-Wave (TDTW) model that properly accounts for coherent radiation-matter interaction in the semiconductor active medium and includes the carrier grating generated by the optical standing wave pattern in the laser cavity. We show that the latter is the fundamental physical effect at the origin of the multi-mode spectrum appearing just above threshold. A self-mode-locking regime associated with the emission of OFC is achieved for higher bias currents and ascribed to nonlinear phase sensitive effects as Four Wave Mixing (FWM). Our results are in very good agreement with the experimental ones.