Direction-Dependent Parity-Time Phase Transition and Non-Reciprocal Directional Amplification with Dynamic Gain-Loss Modulation

TL;DR

This paper demonstrates that dynamic gain-loss modulation in optical structures induces a direction-dependent PT phase transition, enabling thresholdless non-reciprocal directional amplification.

Contribution

It introduces a novel approach to achieve non-reciprocal amplification through direction-dependent PT phase transition with dynamic gain-loss modulation.

Findings

Thresholdless PT phase transition in the forward direction

Non-zero PT threshold in the backward direction

Realization of non-reciprocal directional amplification

Abstract

We show that a dynamic gain-loss modulation in an optical structure can lead to a direction-dependent parity-time (PT) phase transition. The phase transition can be made thresholdless in the forward direction, and yet remains with a non-zero threshold in the backward direction. As a result, non-reciprocal directional amplification can be realized.