Optomechanical Modulation Spectroscopy of Bound-States-In-The-Continuum in a dielectric metasurface

TL;DR

This paper introduces a novel optomechanical modulation spectroscopy technique for detecting narrow-band quasi-Bound-State-in-the-Continuum modes in dielectric metasurfaces, enhancing measurement visibility significantly.

Contribution

The work presents a new spectroscopic method leveraging optomechanical interactions to detect BIC modes, overcoming symmetry protection and background noise challenges.

Findings

Visibility enhancement of over tenfold in measurements

Successful detection of quasi-BIC modes near normal incidence

Potential for precise spectroscopy of symmetry-protected resonances

Abstract

Elusive features in photonic and electronic devices can be detected by means of advanced, time-domain spectroscopic techniques. In this letter we introduce a novel kind of modulation spectroscopy, based on the optomechanical interaction of photonic and mechanical modes. Applying the technique to a Si metasurface and its drum-like mechanical modes, we detect narrow-band quasi-Bound-State-in-the-Continuum (q-BIC) modes close to normal incidence, where their measurement can be hindered by a high symmetry protection and undesired background modes. Showing a visibility enhancement of more than one order of magnitude, the optomechanical modulation spectroscopy can be an innovative tool for precise spectroscopy of a wide set of photonic devices, including the goal of measuring purely symmetry protected BIC resonances.