Experimental characterization of an uniaxial angle cut whispering gallery mode resonator

TL;DR

This paper experimentally investigates an angle-cut whispering gallery mode resonator with arbitrary optic axis orientation, revealing its modal structure, quality factors, and unique polarization properties compared to traditional z-cut and x-cut resonators.

Contribution

It introduces and characterizes the generalized angle-cut resonator, expanding understanding of its modal and polarization behaviors for broadband nonlinear optics applications.

Findings

Modal structure similar to standard resonators

Quality factors comparable to traditional designs

Polarization varies with position and is generally elliptical

Abstract

The usual configuration of uniaxial whispering gallery mode resonators is a disk shaped geometry where the optic axis points along the symmetry axis, a so called z-cut resonator. Recently x-cut resonators, where the optic axis lies in the equatorial plane, became of interest as they enable extremely broadband second harmonic generation. In this paper we report on the properties of a more generalized system, the so called angle-cut resonator, where the optic axis exhibits an arbitrary angle against the symmetry axis. We show experimentally that the modal structure and quality factors are similar to common resonators but that the polarization properties differ quite significantly: due to the asymmetry the polarization depends on the equatorial position and is, in general, elliptical.