Dispersion-induced dynamics of coupled modes in a semiconductor laser with saturable absorption

TL;DR

This study investigates the complex nonlinear dynamics of dual-mode semiconductor lasers with saturable absorption, revealing how dispersion influences mode interactions and stability, with implications for designing tailored mode-locked lasers.

Contribution

The paper combines experimental and theoretical analysis to show how dispersion-induced effects lead to complex multimode dynamics in semiconductor lasers with saturable absorbers.

Findings

Single mode self-pulsations evolve into complex bursting states

Modes follow symmetric, oppositely directed spiralling orbits

Material dispersion influences the stability of multimode states

Abstract

We present an experimental and theoretical study of modal nonlinear dynamics in a specially designed dual-mode semiconductor Fabry-Perot laser with a saturable absorber. At zero bias applied to the absorber section, we have found that with increasing device current, single mode self-pulsations evolve into a complex dynamical state where the total intensity experiences regular bursts of pulsations on a constant background. Spectrally resolved measurements reveal that in this state the individual modes of the device can follow highly symmetric but oppositely directed spiralling orbits. Using a generalization of the rate equation description of a semiconductor laser with saturable absorption to the multimode case, we show that these orbits appear as a consequence of the interplay between the material dispersion in the gain and absorber sections of the laser. Our results provide insights into the factors that determine the stability of multimode states in these systems, and they can inform the development of semiconductor mode-locked lasers with tailored spectra.