The large electro-optic coefficient, r₃₃, of thin-film lithium niobate (LN) on insulator makes it an excellent material platform for high-efficiency optical modulators. Using the fundamental transverse magnetic optical mode in Z-cut LN enables isotropic in-plane devices; however, realizing a strong vertical electric field to capitalize on r₃₃ has been challenging. Here we present a symmetric electrode configuration to boost the vertical field strength inside a fully-etched single-mode LN waveguide. We use this design paradigm to demonstrate an ultra-compact fully isotropic microring modulator with a high electro-optic tuning efficiency of 9 pm/V, extinction ratio of 20 dB, and modulation bandwidth beyond 28 GHz. Under quasi-static operation, the tuning efficiency of the modulator reaches 20 pm/V. Fast, efficient, high-contrast modulation will be critical in future optical communication systems while large quasi-static efficiency will enable post-fabrication trimming, thermal compensation, and even complete reconfiguration of microring-based sensor arrays and photonic integrated circuits.

中文翻译：

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薄膜铌酸锂光子平台中的超高效且各向同性的单片微环调制器

绝缘体上的薄膜铌酸锂（LN）的大电光系数r ₃₃使其成为高效光学调制器的绝佳材料平台。在Z形切割LN中使用基本横向磁光学模式可以实现各向同性的面内器件；然而，利用r ₃₃实现强大的垂直电场一直充满挑战。在这里，我们提出一种对称电极配置，以提高完全蚀刻的单模LN波导内部的垂直场强度。我们使用这种设计范例来演示一种超紧凑的全同性微环调制器，该调制器具有9 pm / V的高电光调谐效率，20 dB的消光比以及超过28 GHz的调制带宽。在准静态操作下，调制器的调谐效率达到20 pm / V。快速，高效，高对比度的调制在未来的光通信系统中将至关重要，而大的准静态效率将使制造后的修整，热补偿，甚至完全重新配置基于微环的传感器阵列和光子集成电路。