Polarization conversion loss in birefringent crystalline resonators

TL;DR

This paper investigates how birefringence and resonator shape affect polarization conversion loss and quality factors in whispering gallery modes of crystalline resonators, revealing that extraordinary modes can be suppressed due to polarization conversion.

Contribution

It provides experimental insights into polarization conversion loss in birefringent crystalline resonators, highlighting the impact of shape and birefringence on mode quality factors.

Findings

Extraordinary modes can have lower Q or be suppressed due to polarization conversion loss.

Ordinary ray modes maintain high Q due to inhibited reflection.

Resonator shape and birefringence significantly influence mode quality factors.

Abstract

Whispering gallery modes in birefringent crystalline resonators are investigated. We experimentally investigate the XY--cut resonators made with LiNbO$_3$, LiTaO$_3$ and BBO and observe strong influence of the resonator's shape and birefringence on the quality factor of the extraordinary polarized modes. We show that extraordinary modes can have lower Q and even be suppressed due to polarization conversion loss. The ordinary ray modes retain the high Q due to inhibited reflection phenomenon.