Non-Hermitian Optical Parametric Systems with Anti-parity-time Symmetry

TL;DR

This paper explores non-Hermitian optical parametric systems with anti-PT symmetry, revealing complex behaviors and exceptional points that could advance photonics and laser science applications.

Contribution

It introduces a novel approach to non-Hermitian nonlinear parametric amplification using anti-PT symmetry, categorizing system behaviors in parameter space and analyzing eigenmode dynamics.

Findings

Identification of four distinct symmetry quadrants in parameter space.

Observation of exceptional points and their effects on wave evolution.

Insights into energy flow and system behavior near symmetry-breaking boundaries.

Abstract

The continuous advancements in ultrafast lasers, characterized by high pulse energy, great average power, and ultrashort pulse duration, have opened up new frontiers and applications in various fields such as high-energy-density science. In this study, we investigated the implementation of non-Hermitian nonlinear parametric amplification by introducing anti-parity-time (anti-PT) symmetry to three-wave interaction processes. By exploring the parameter space defined by the coupling coefficient, phase mismatch, and absorption, we categorized the behavior of the non-Hermitian optical parametric system into four distinct quadrants, representing unbroken/broken anti-PT symmetry and amplification/attenuation, and amplification-attenuation boundaries and exceptional lines can be observed in such parametric space. Through simulations of the dynamical behavior of the interacting waves, we demonstrated the rich evolutions of the signal and idler waves in systems belonging to the respective quadrants and near exceptional points, revealed by the unique performance of eigenmodes. Our findings provide insights into the evaluation of energy flow direction in optical parametric amplification engineering by the directly linked parameter space, which contribute to a deeper understanding of photonics and laser science, potentially leading to new applications in these fields.