Single mode lasing in transversely multi-moded PT-symmetric microring resonators

TL;DR

This paper demonstrates single mode lasing in a PT-symmetric microring system, leveraging exceptional points for mode discrimination, leading to stable, pure, chip-scale semiconductor lasers with potential for robust practical applications.

Contribution

It introduces a novel PT-symmetric double microring design that achieves stable single mode lasing through mode discrimination at exceptional points, resilient to fabrication errors.

Findings

Successful experimental demonstration of single mode lasing

Stable operation above threshold with high spectral purity

Robustness to small fabrication errors

Abstract

Single mode lasing is experimentally demonstrated in a transversely multi-moded InP-based semiconductor microring arrangement. In this system, mode discrimination is attained by judiciously utilizing the exceptional points in a parity-time (PT) symmetric double microring configuration. The proposed scheme is versatile, robust to small fabrication errors, and enables the device to operate in a stable manner considerably above threshold while maintaining spatial and spectral purity. The results presented here pave the way towards a new class of chip-scale semiconductor lasers that utilize gain/loss contrast as a primary mechanism for mode selection.