Tunable linear and quadratic optomechanical coupling for a tilted membrane within an optical cavity: theory and experiment

TL;DR

This paper demonstrates tunable linear and quadratic optomechanical coupling in a membrane-in-cavity system, showing how membrane positioning affects coupling strength and revealing large quadratic coupling at avoided crossings, supported by experimental and theoretical analysis.

Contribution

It introduces a method to tune optomechanical coupling via membrane position and orientation, and provides experimental and theoretical insights into quadratic coupling phenomena.

Findings

Tunable optomechanical coupling achieved by membrane positioning.

Large quadratic coupling observed at avoided crossings.

Experimental results align with perturbation theory predictions.

Abstract

We present an experimental study of an optomechanical system formed by a vibrating thin semi-transparent membrane within a high-finesse optical cavity. We show that the coupling between the optical cavity modes and the vibrational modes of the membrane can be tuned by varying the membrane position and orientation. In particular we demonstrate a large quadratic dispersive optomechanical coupling in correspondence with avoided crossings between optical cavity modes weakly coupled by scattering at the membrane surface. The experimental results are well explained by a first order perturbation treatment of the cavity eigenmodes.