Lithium niobate (LN) is an ideal material for electrooptic (EO) modulation due to its strong EO effect. However, significant differences exist in the EO modulation efficiencies for different polarizations, given the anisotropy of LN. Here, we propose an innovative approach to mitigate the modulation polarization dependence of thin-film LN. We convert one of the orthogonal polarizations of the incident light to the higher-order mode of the other polarization and utilize mode-compatible components to achieve mode-independent signal processing, thereby converting the polarization issue into a mode issue and achieving polarization-independent signal processing. We also demonstrated a polarization-insensitive EO switch to validate this approach. The fabricated device demonstrates a low polarization-dependent loss of 0–2.4 dB across a 30 nm range (1260–1290 nm) and achieves the same modulation efficiency of 2.7 V·cm for TE and TM polarizations. The approach provides a robust solution to the EO modulation polarization dependence problem caused by the anisotropy in LN and other similar materials.

中文翻译：

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各向异性薄膜铌酸锂的偏振不敏感电光调制


铌酸锂（LN）由于其强大的EO效应而成为电光（EO）调制的理想材料。然而，考虑到 LN 的各向异性，不同偏振的电光调制效率存在显着差异。在这里，我们提出了一种创新方法来减轻薄膜 LN 的调制偏振依赖性。我们将入射光的一个正交偏振转换为另一个偏振的高阶模式，并利用模式兼容的组件来实现模式无关的信号处理，从而将偏振问题转化为模式问题，获得偏振无关的信号加工。我们还演示了一种对偏振不敏感的电光开关来验证这种方法。所制造的器件在 30 nm 范围 (1260–1290 nm) 内表现出 0–2.4 dB 的低偏振相关损耗，并且对于 TE 和 TM 偏振实现了 2.7 V·cm 的相同调制效率。该方法为 LN 和其他类似材料的各向异性引起的 EO 调制偏振相关问题提供了稳健的解决方案。