Single-mode laser by parity-time symmetry breaking

TLDR

Effective manipulation of cavity resonant modes is crucial for emission control in laser physics, and exploring parity‑time symmetry may enable next‑generation optoelectronic devices for optical communications and computing. Using the concept of parity‑time symmetry to exploit the interplay between gain and loss, we demonstrate a parity‑time symmetry‑breaking laser with resonant modes that can be controlled at will. The laser employs a parity‑time symmetric microring structure that balances gain and loss to achieve controllable resonant modes. Our parity‑time microring laser exhibits intrinsic single‑mode lasing regardless of the gain spectral bandwidth, and thresholdless parity‑time symmetry breaking due to the rotationally symmetric structure leads to stable single‑mode operation with selective whispering‑gallery mode order.

Abstract

Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and applications. Using the concept of parity-time symmetry to exploit the interplay between gain and loss (i.e., light amplification and absorption), we demonstrate a parity-time symmetry-breaking laser with resonant modes that can be controlled at will. In contrast to conventional ring cavity lasers with multiple competing modes, our parity-time microring laser exhibits intrinsic single-mode lasing regardless of the gain spectral bandwidth. Thresholdless parity-time symmetry breaking due to the rotationally symmetric structure leads to stable single-mode operation with the selective whispering-gallery mode order. Exploration of parity-time symmetry in laser physics may open a door to next-generation optoelectronic devices for optical communications and computing.