Chaotic Microcavity Laser with Low threshold and Unidirectional Output

TL;DR

This paper demonstrates lasing in chaotic limaçon-shaped GaAs microdisks with quantum dots, achieving low thresholds and unidirectional emission due to wave localization and phase space flow, robust against shape deviations.

Contribution

It introduces a chaotic microcavity laser with low threshold and unidirectional output, leveraging wave localization and phase space dynamics for robust emission direction.

Findings

High-Q modes are localized despite chaotic dynamics.

Lasing modes emit unidirectionally in the same direction.

The unidirectional emission is robust to cavity shape deviations.

Abstract

Here we report lasing action in lima\c{c}on-shaped GaAs microdisks with quantum dots (QDs) embedded. Although the intracavity ray dynamics is predominantly chaotic, high-$Q$ modes are concentrated in the region $\chi > \chi_c$ as a result of wave localization. Strong optical confinement by total internal reflection leads to very low lasing threshold. Our measurements show that all the lasing modes have output in the same direction, regardless of their wavelengths and intracavity mode structures. This universal emission direction is determined by directed phase space flow of optical rays in the open chaotic cavity. The divergence angle of output beam is less than 40 degree. The unidirectionality proves to be robust against small deviations of the real cavity shape and size from the designed values.