Nonlinear behaviors of parity-time-symmetric lasers

TL;DR

This paper develops a PDE model to study the nonlinear dynamics of PT-symmetric lasers, revealing how loss influences their mode stability and operation.

Contribution

It introduces a comprehensive time-dependent PDE model that includes key physical effects to analyze PT laser behaviors during nonlinear operation.

Findings

Weak loss leads to multi-mode stable states and periodic light states.

Strong loss results in a single stable broken PT symmetry state.

Loss plays a crucial role in laser mode stability.

Abstract

We propose a time-dependent partial differential equation model to investigate the dynamical behavior of the parity-time (PT) symmetric laser during the nonlinear stage of its operation. This model incorporates physical effects such as the refractive index distribution, dispersion, material loss, nonlinear gain saturation and self-phase modulation. We show that when the loss is weak, multiple stable steady states and time-periodic states of light exist above the lasing threshold, rendering the laser multi-mode. However, when the loss is strong, only a single stable steady state of broken PT symmetry exists for a wide range of the gain amplitude, rendering the laser single-mode. These results reveal the important role the loss plays in maintaining the single-mode operation of PT lasers.