Symmetry-protected zero-mode laser with a tunable spatial profile

TL;DR

This paper introduces a tunable, single-mode laser based on symmetry-protected zero modes in a non-Hermitian photonic lattice, enabling spatial profile control without frequency alteration.

Contribution

It demonstrates a novel approach to laser design utilizing non-Hermitian symmetry-protected zero modes for spatial tunability and robustness against disorder.

Findings

Achieved spatially tunable laser emission

Demonstrated robustness to disorder

Controlled symmetry restoration for profile tuning

Abstract

We propose to utilize symmetry-protected zero modes of a photonic lattice to realize a single-mode, fixed-frequency, and spatially tunable laser. These properties are the consequence of the underlying non-Hermitian particle-hole symmetry, with which the energy spectrum satisfies $\varepsilon_m=-\varepsilon_n^*$. Unlike in the Hermitian case, the symmetric phase of particle-hole symmetry is no longer restricted to $\varepsilon=0$ but extends along the imaginary-$\varepsilon$ axis, which is set by the single-cavity frequency and symmetry-protected against position and coupling disorder of the photonic lattice. By selectively pumping different cavities in the photonic lattice, we control the spontaneous symmetry restoration process, which provides a convenient method to tune the spatial profile of the laser without changing its frequency.