Polarization conversion loss in birefringent crystalline resonators.

Whispering gallery modes in birefringent crystalline resonators are investigated. We experimentally investigate the XY-cut resonators made with LiNbO3, LiTaO3, 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 owing to polarization conversion loss. The ordinary ray modes retain the high Q due to inhibited reflection phenomenon.