Pseudo Parity-Time Symmetry in Optical Systems

TL;DR

This paper introduces the concept of pseudo parity-time symmetry in optical systems, showing how periodic modulation can induce effective $ ext{PT}$ symmetry in systems regardless of their original symmetry, enabling control over light propagation.

Contribution

The study demonstrates a method to manipulate $ ext{PT}$ symmetry via high-frequency Floquet modulation, creating pseudo $ ext{PT}$ symmetry in non-$ ext{PT}$ symmetric systems.

Findings

Effective $ ext{PT}$ symmetry can be induced in non-$ ext{PT}$ symmetric systems.

Periodic modulation leads to quasi-stationary light propagation.

The approach offers new ways to control optical system properties.

Abstract

We introduce a novel concept of the {\em pseudo} parity-time ($\mathcal{PT}$) symmetry in periodically modulated optical systems with balanced gain and loss. We demonstrate that whether the original system is $\mathcal{PT}$-symmetric or not, we can manipulate the property of the $\mathcal{PT}$ symmetry by applying a periodic modulation in such a way that the effective system derived by the high-frequency Floquet method is $\mathcal{PT}$ symmetric. If the original system is non-$\mathcal{PT}$ symmetric, the $\mathcal{PT}$ symmetry in the effective system will lead to quasi-stationary propagation that can be associated with the \emph{pseudo $\mathcal{PT}$ symmetry}. Our results provide a promising approach for manipulating the $\mathcal{PT}$ symmetry of realistic systems.