Response of a multi-wavelength laser to single-sideband optical injection

TL;DR

This study explores how a dual-wavelength on-chip laser responds to single-sideband optical injection, revealing asymmetric sideband power evolution and dependence on injection parameters, with implications for optical signal processing.

Contribution

It provides the first combined numerical and experimental analysis of multi-wavelength laser dynamics under single-sideband optical injection, highlighting controllable spectral features.

Findings

Asymmetric sideband power evolution observed.

Sideband characteristics depend on injection detuning and strength.

Numerical results closely match experimental data.

Abstract

Single-mode semiconductor lasers subject to optical injection have been shown to trigger a wide range of dynamical behavior from injection locking to chaos. Multi-wavelength lasers add even more degrees of freedom and complexity to the dynamical repertoire potentially unlocking new functionalities for applications ranging from THz generation and processing to all-optical memories. In particular, leveraging the inherent mode coupling in multi-wavelength lasers, spectral multiplication over a THz range of an injected optical signal has been shown. While most of the research on optical injection has been focused on single-mode semiconductor lasers, the dynamical behavior of multi-wavelength lasers, particularly when subjected to injection of amplitude-modulated signals remains vastly unexplored. In this work, we numerically and experimentally investigate the response of an on-chip dual-wavelength laser subject to the optical injection of a single-sideband signal around one of the modes of the laser. Our findings show an asymmetric power evolution of the sidebands appearing around both the injected and un-injected modes with respect to the modulation frequency. The power and bandwidth of the sideband signals strongly depend on the resonance frequency produced by the interference between the cavity mode and the injection, which can be tailored by twerking the strength and the detuning of the injection. The outcomes of our numerical investigations, based on rate equations, align closely with the experimental results highlighting the influence of key injection and laser parameters.