Self-dual Spectral Singularities and Coherent Perfect Absorbing Lasers without PT-symmetry

TL;DR

This paper demonstrates that self-dual spectral singularities and CPA-lasers can exist in non-PT-symmetric optical systems, expanding the understanding of spectral singularities beyond PT-symmetry constraints.

Contribution

It reveals the emergence of self-dual spectral singularities and CPA-lasers in non-PT-symmetric configurations, challenging previous assumptions about PT-symmetry requirements.

Findings

Self-dual spectral singularities can occur without PT-symmetry.

Non-PT-symmetric CPA-lasers are theoretically possible.

Spectral singularities are not exclusive to PT-symmetric systems.

Abstract

A PT-symmetric optically active medium that lases at the threshold gain also acts as a complete perfect absorber at the laser wavelength. This is because spectral singularities of PT-symmetric complex potentials are always accompanied by their time-reversal dual. We investigate the significance of PT-symmetry for the appearance of these self-dual spectral singularities. In particular, using a realistic optical system we show that self-dual spectral singularities can emerge also for non-PT-symmetric configurations. This signifies the existence of non-PT-symmetric CPA-lasers.