Intrinsically single-mode cavities: towards PT-symmetric surface-emitting lasers

TL;DR

This paper introduces a novel PT-symmetric cavity design for surface-emitting lasers that inherently supports only a single longitudinal mode, promising advancements in laser stability and coherence.

Contribution

It presents a new PT-symmetric DFB structure enabling inherently single-mode surface-emitting lasers, supported by theoretical analysis and exact solutions.

Findings

PT-symmetric gratings enable single-mode operation

Theoretical analysis confirms threshold and spectral properties

Design supports stable, single-mode lasing

Abstract

We explore a new class of Distributed Feedback (DFB) structures that employ the recently-developed concept of Parity-Time (PT) symmetry in optics. We demonstrate that, based on PT-symmetric pure reflective volume gratings, vertical cavity surface-emitting lasers can be constructed. We provide a detailed analysis of the threshold conditions as well as the wavelength and angular spectral characteristics using the Kogelnik coupled-wave approximation, backed up by an exact solution of the Helmholtz equation. We demonstrate that such a PT-symmetric cavity can be configured to support one and only one longitudinal mode, leading to inherently single-mode lasing.