Thermo-optical bistability in silicon micro-cantilevers

TL;DR

This paper reports the observation of thermo-optical bistability in silicon micro-cantilevers caused by internal reflections acting as a lossy Fabry-Pérot cavity, with experimental results matching a theoretical model.

Contribution

It introduces a theoretical model explaining thermo-optical bistability in silicon micro-cantilevers due to internal interference effects.

Findings

Bistability occurs at mW laser powers in silicon micro-cantilevers.

Reflectivity, transmissivity, absorption, and temperature can switch between two stable states.

Experimental results align with the theoretical model predictions.

Abstract

We report a thermo-optical bistability observed in silicon micro-cantilevers irradiated by a laser beam with mW powers: reflectivity, transmissivity, absorption, and temperature can change by a factor of two between two stable states for the same input power. The temperature dependency of the absorption at the origin of the bistability results from interferences between internal reflections in the cantilever thickness, acting as a lossy Fabry-P\'erot cavity. A theoretical model describing the thermo-optical coupling is presented. The experimental results obtained for silicon cantilevers irradiated in vacuum at two different visible wavelengths are in quantitative agreement with the predictions of this model.