# Nonreciprocal transmission and fast-slow light effects in a cavity optomechanical system

## TL;DR

This paper investigates nonreciprocal transmission and fast-slow light effects in a cavity optomechanical system with counter-rotating optical modes driven by strong pump and weak signal fields, revealing conditions for nonreciprocity.

## Contribution

It demonstrates how nonreciprocal transmission and fast-slow light effects depend on the cavity's photon loss rates, providing insights into controlling light propagation in optomechanical systems.

## Key findings

- Nonreciprocal transmission occurs when intrinsic and external losses are balanced.
- Nonreciprocal group delay is observed when intrinsic loss is much less than external coupling.
- System exhibits controllable fast-slow light propagation phenomena.

## Abstract

We study the nonreciprocal transmission and the fast-slow light effects in a cavity optomechanical system, in which the cavity supports a clockwise and a counter-clockwise circulating optical modes, both the two modes are driven simultaneously by a strong pump field and a weak signal field. We find that when the intrinsic photon loss of the cavity is equal to the external coupling loss of the cavity, the system reveals a nonreciprocal transmission of the signal fields. However, when the intrinsic photon loss is much less than the external coupling loss, the nonreciprocity about the transmission properties almost disappears, and the nonreciprocity is shown in the group delay properties of the signal fields, and the system exhibits a nonreciprocal fast-slow light propagation phenomenon.