Optical circulation in a multimode optomechanical resonator

TL;DR

This paper demonstrates a magnet-free, reconfigurable optical circulator on-chip using radiation pressure in a multimode optomechanical system, achieving high isolation and low loss for integrated photonic circuits.

Contribution

It introduces a novel optomechanical approach to realize reconfigurable optical circulation without magnetic bias, enabling integrated nanophotonic circuit applications.

Findings

Achieved ~10 dB isolation and <3 dB insertion loss in all channels.

Demonstrated active control over bandwidth, isolation ratio, and circulation direction.

Identified conditions for ideal optical circulation in a multimode system.

Abstract

Optical circulators are important components of modern day communication technology. With their ability to route photons directionally, these nonreciprocal elements provide useful functionality in photonic circuits and offer prospects for fundamental research on information processing. Developing highly efficient optical circulators thus presents an important challenge, in particular to realize compact reconfigurable implementations that do not rely on a magnetic field bias to break reciprocity. We demonstrate optical circulation based on radiation pressure interactions in an on-chip multimode optomechanical system. We show that mechanically-mediated optical mode conversion in a silica microtoroid provides a synthetic gauge bias for light, which enables a 4-port circulator by exploiting tailored interference between appropriate light paths. We identify two sideband conditions under which ideal circulation is approached. This allows to experimentally demonstrate $\sim$10 dB isolation and $<$ 3 dB insertion loss in all relevant channels. We show the possibility of actively controlling the bandwidth, isolation ratio, noise performance and circulation direction, enabling ideal opportunities for reconfigurable integrated nanophotonic circuits.