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.

中文翻译：

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低温铌酸锂环形谐振器中的光折射引起的布拉格散射

我们报道了在低温下高$ Q $铌酸锂环形谐振腔中的光折变（PR）效应引起的腔内布拉格散射。我们表明，当腔模被强烈激发时，PR效应印制了一个长寿命的周期性空间电荷场。该残留场又产生折射率调制图案，该图案显着增强了入射探针光的向后散射，并导致选择性和可重新配置的模式分裂。尽管许多应用都不希望这种PR引起的布拉格散射效应，但可以利用它来实现光学可编程的光子组件。