Optical microcavity characterization via resonance spectra and modes

TL;DR

This paper develops a semi-analytic theory to characterize optical microcavities using resonance spectra and mode profiles, accounting for mirror shape and nonparaxial effects, and demonstrates how these effects influence mode properties.

Contribution

It extends existing nonparaxial theory to anisotropic Gaussian mirrors and provides a method to distinguish and quantify mode-shaping effects in microcavities.

Findings

Resonance spectra reveal mode-shaping effects.

Polarization patterns indicate spin-orbit coupling.

Polarization tomography quantifies birefringence.

Abstract

This paper describes how resonance spectra and mode profiles can be used to characterize and quantify the mode-shaping effects in open-access plano-concave optical microcavities. The presented semi-analytic theory is based on the application of perturbation theory to the roundtrip evolution of the optical field. It includes various mirror-shape and nonparaxial effects and extends the nonparaxial theory presented by van Exter et al. (2022, Phys. Rev. A 106, 013501) and verified by Koks et al. (2022, Phys. Rev. A 105, 063502) to the common case of an anisotropic Gaussian mirror. The presented measurements and analyses of resonance spectra and mode profiles demonstrate how the different mode-shaping effects can be individually distinguished and quantified. Spin-orbit coupling, which is one of the nonparaxial effects, is prominently visible in the intriguing polarization patterns of the resonant modes, while polarization tomography yields the shape-induced birefringence and associated polarization splitting of the fundamental modes.