Optical and mechanical mode tuning in an optomechanical crystal with light-induced thermal effects

TL;DR

This paper investigates how light-induced heating affects the optical and mechanical properties of a silicon optomechanical crystal cavity, demonstrating the thermal tuning effects through experiments and simulations.

Contribution

It provides a combined experimental and simulation analysis of thermo-optic effects on optomechanical crystal modes, linking temperature increase to mode shifts.

Findings

Optical modes shift to longer wavelengths with heating.

Mechanical modes decrease in frequency due to temperature rise.

Finite element simulations agree with experimental mode shifts.

Abstract

We report on the modification of the optical and mechanical properties of a silicon 1D optomechanical crystal cavity due to thermo-optic effects in a high phonon/photon population regime. The cavity heats up due to light absorption in a way that shifts the optical modes towards longer wavelengths and the mechanical modes to lower frequencies. By combining the experimental optical results with finite-difference time-domain simulations we establish a direct relation between the observed wavelength drift and the actual effective temperature increase of the cavity. By assuming that the Young's modulus decreases accordingly to the temperature increase, we find a good agreement between the mechanical mode drift predicted using a finite element method and the experimental one.