Optomechanical transistor with mechanical gain

TL;DR

This paper proposes an optomechanical transistor that achieves unidirectional amplification and nonreciprocity through mechanical gain and phase control, enabling efficient light transport and signal amplification.

Contribution

It introduces a novel cyclic three-mode optomechanical system utilizing mechanical gain for nonreciprocal amplification and long-delay control of light.

Findings

Achieves perfect unidirectionality with strong amplification.

Demonstrates mechanical gain induces ultra-long phase delay.

Shows nonreciprocity arises from phase difference breaking time-reversal symmetry.

Abstract

We study an optomechanical transistor, where an input field can be transferred and amplified unidirectionally in a cyclic three-mode optomechanical system. In this system, the mechanical resonator is coupled simultaneously to two cavity modes. We show that it only requires a finite mechanical gain to achieve the nonreciprocal amplification. Here the nonreciprocity is caused by the phase difference between the linearized optomechanical couplings that breaks the time-reversal symmetry of this system. The amplification arises from the mechanical gain, which provides an effective phonon bath that pumps the mechanical mode coherently. This effect is analogous to the stimulated emission of atoms, where the probe field can be amplified when its frequency is in resonance with that of the anti-Stokes transition. We show that by choosing optimal parameters, this optomechanical transistor can reach perfect unidirectionality accompanied with strong amplification. In addition, the presence of the mechanical gain can result in ultra-long delay in the phase of the probe field, which provides an alternative to controlling light transport in optomechanical systems.