Floquet control of the gain and loss in a PT-symmetric optical coupler

TL;DR

This paper demonstrates how periodic Floquet modulation can control and extend the PT-symmetric phase in optical couplers, transforming non-Hermitian systems into effective Hermitian ones for improved stability.

Contribution

It introduces a Floquet-based method to manipulate gain and loss in PT-symmetric systems, broadening the unbroken PT-symmetric parameter range.

Findings

Periodic modulation effectively controls gain and loss.

High-frequency Floquet theory transforms non-Hermitian systems into Hermitian.

The method extends the unbroken PT-symmetric regime.

Abstract

Controlling the balanced gain and loss in a PT-symmetric system is a rather challenging task. Utilizing Floquet theory, we explore the constructive role of periodic modulation in controlling the gain and loss of a PT-symmetric optical coupler. It is found that the gain and loss of the system can be manipulated by applying a periodic modulation. Further, such an original non-Hermitian system can even be modulated into an effective Hermitian system derived by the high-frequency Floquet method. Therefore, compared with other PT symmetry control schemes, our protocol can modulate the unbroken PT-symmetric range to a wider parameter region. Our results provide a promising approach for controlling the gain and loss of a realistic system.