Multi-stabilities and symmetry-broken one-colour and two-colour states in closely coupled single-mode lasers

TL;DR

This paper explores the complex dynamics of two closely coupled single-mode semiconductor lasers, revealing stable symmetry-broken states and multi-stability phenomena that can be utilized for designing all-optical memory devices.

Contribution

It introduces a detailed bifurcation analysis of coupled lasers, identifying conditions for symmetry-broken states and their potential for optical memory applications.

Findings

Stable symmetry-broken one-colour states at small separation and large coupling.

Existence of stable symmetry-broken two-colour states with frequency separation up to 150 GHz.

Multi-stability enabling all-optical memory design.

Abstract

We theoretically investigate the dynamics of two mutually coupled identical single-mode semi-conductor lasers. For small separation and large coupling between the lasers, symmetry-broken one-colour states are shown to be stable. In this case the light output of the lasers have significantly different intensities while at the same time the lasers are locked to a single common frequency. For intermediate coupling we observe stable symmetry-broken two-colour states, where both lasers lase simultaneously at two optical frequencies which are separated by up to 150~GHz. Using a five dimensional model we identify the bifurcation structure which is responsible for the appearance of symmetric and symmetry-broken one-colour and two-colour states. Several of these states give rise to multi-stabilities and therefore allow for the design of all-optical memory elements on the basis of two coupled single-mode lasers. The switching performance of selected designs of optical memory elements is studied numerically.