Photorefraction-induced Bragg scattering in cryogenic lithium niobate ring resonators

We report intracavity Bragg scattering induced by the photorefractive (PR) effect in high- Q lithium niobate ring resonators at cryogenic temperatures. We show that when a cavity mode is strongly excited, the PR effect imprints a long-lived periodic space-charge field. This residual field in turn creates a refractive index modulation pattern that dramatically enhances the back scattering of an incoming probe light, and results in selective and reconfigurable mode splittings. This PR-induced Bragg scattering effect, despite being undesired for many applications, could be utilized to enable optically programmable photonic components. (C) 2021 Optical Society of America

Automated summary

In high-Q lithium niobate ring resonators at cryogenic temperatures, intracavity Bragg scattering induced by the photorefractive effect was observed to create a long-lived periodic space-charge field imprinting a refractive index modulation pattern. This phenomenon enhances back scattering of incoming light and leads to selective and reconfigurable mode splittings. Despite being undesired for many applications, this photorefractive-induced Bragg scattering effect could be utilized to enable optically programmable photonic components.