Dynamical backaction in an ultrahigh-finesse fiber-based microcavity

TL;DR

This paper reports the development of an ultrahigh-finesse fiber-based microcavity with enhanced light-matter interaction, enabling sensitive displacement detection and demonstrating radiation pressure backaction in a highly reflective cavity.

Contribution

It introduces a fiber-based microcavity with the highest finesse reported, achieving tunable optomechanical coupling and observing backaction effects at ultrahigh finesse levels.

Findings

Finesse of 195,000 achieved in loaded fiber cavities

Tunable static optomechanical coupling with a silicon nitride membrane

Observation of radiation pressure backaction at finesse up to 165,000

Abstract

The use of low-dimensional objects in the field of cavity optomechanics is limited by their low scattering cross section compared to the size of the optical cavity mode. Fiber-based Fabry-P\'{e}rot microcavities can feature tiny mode cross sections and still maintain a high finesse, boosting the light-matter interaction and thus enabling the sensitive detection of the displacement of minute objects. Here we present such an ultrasensitive microcavity setup with the highest finesse reported so far in loaded fiber cavities, $\mathcal{F} = 195\,000$. We are able to position-tune the static optomechanical coupling to a silicon nitride membrane stripe, reaching frequency pull parameters of up to $\mathrm{\lvert G/2\pi\rvert=1}\,\mathrm{GHz\, nm^{-1}}$. We also demonstrate radiation pressure backaction in the regime of an ultrahigh finesse up to $\mathcal{F}=165\,000$.