Optical back-action on the photothermal relaxation rate

TL;DR

This paper demonstrates an optical back-action effect on the photothermal relaxation rate in a cavity, enabling precise in-situ measurement of photothermal parameters and control of the relaxation process.

Contribution

It introduces an experimental method to observe and utilize optical back-action to control and measure photothermal relaxation rates in optical cavities.

Findings

Photothermal relaxation rate can be modified by over an order of magnitude.

The method allows precise in-situ estimation of cavity parameters.

Optical detuning controls the photothermal relaxation process.

Abstract

Photothermal effects can alter the response of an optical cavity, for example, by inducing self-locking behavior or unstable anomalies. The consequences of these effects are often regarded as parasitic and generally cause limited operational performance of the cavity. Despite their importance, however, photothermal parameters are usually hard to characterize precisely. In this work we use an optical cavity strongly coupled to photothermal effects to experimentally observe an optical back-action on the photothermal relaxation rate. This effect, reminiscent of the radiation-pressure-induced optical spring effect in cavity optomechanical systems, uses optical detuning as a fine control to change the photothermal relaxation process. The photothermal relaxation rate of the system can be accordingly modified by more than an order of magnitude. This approach offers an opportunity to obtain precise in-situ estimations of the parameters of the cavity, in a way that is compatible with a wide range of optical resonator platforms. Through this back-action effect we are able to determine the natural photothermal relaxation rate and the effective thermal conductivity of the cavity mirrors with unprecedented resolution.