The combination of directional outputs and single-mode operation in circular microdisk with broken PT symmetry

TL;DR

This paper presents a novel on-chip microdisk laser design that achieves single-mode operation and directional emission by leveraging PT symmetry and periodic gain-loss modulation, addressing key challenges in laser miniaturization.

Contribution

It introduces a new microdisk laser structure combining PT symmetry and periodic gain-loss modulation to enable simultaneous single-mode and directional emission.

Findings

Achieves single-mode operation with low threshold.

Demonstrates directional emission via periodic gain-loss distribution.

Potential for improved on-chip laser applications.

Abstract

Monochromaticity and directionality are two key characteristics of lasers. However, the combination of directional emission and single-mode operation is quite challenging, especially for the on-chip devices. Here we propose a microdisk laser with single-mode operation and directional emissions by exploiting the recent developments associated with parity-time (PT) symmetry. This is accomplished by introducing one-dimensional periodic gain and loss into a circular microdisk, which induces a coupling between whispering gallery modes with different radial numbers. The lowest threshold mode is selected at the positions with least initial wavelength difference. And the directional emissions are formed by the introduction of additional grating vectors by the periodic distribution of gain and loss regions. We believe this research will impact the practical applications of on-chip microdisk lasers.