Dark-field imaging as a non-invasive method for characterization of whispering gallery modes in microdisk cavities

TL;DR

This paper demonstrates a non-invasive dark-field imaging technique to visualize and characterize whispering gallery modes in microdisk cavities, providing detailed mode information and optical density insights.

Contribution

It introduces a simple, non-invasive method using dark-field imaging and spectroscopy to analyze whispering gallery modes in microdisk cavities.

Findings

Visualized spatial intensity distribution of modes

Extracted azimuthal, radial, and axial mode indices

Provided optical density information via scattering spectrum

Abstract

Whispering gallery mode microdisk cavities fabricated by direct laser writing are studied using dark-field imaging and spectroscopy in the visible spectral range. {Dark-field imaging allows us to directly visualize the spatial intensity distribution of whispering gallery modes. We extract their azimuthal and radial mode indices from dark-field images, and find the axial mode number from the dispersion relation. The scattering spectrum obtained in the confocal arrangement provides information on the density of optical states in the resonator. The proposed technique is a simple non-invasive way to characterize the optical properties of microdisk cavities.