Photonic devices based on ferroelectric domain engineering in thin film lithium niobate are key components for both classical and quantum information processing. Periodic poling of ridge waveguide can avoid the selective etching effect of lithium niobate, however, the fabrication of high-quality ferroelectric domain is still a challenge. In this work, we optimized the applied electric field distribution, and rectangular inverted domain structure was obtained in the ridge waveguide which is beneficial for efficient nonlinear frequency conversions. Second harmonic confocal microscope, piezoresponse force microscopy, and chemical selective etching were used to characterize the inverted domain in the ridge waveguide. In addition, the performance of nonlinear frequency conversion of the periodically poled nano-waveguide was investigated through second harmonic generation, and the normalized conversion efficiency was measured to be 1,720 % W−1 cm−2, which is close to 60 % that of the theoretical value. The fabrication technique described in this work will pave the way for the development of high-efficiency, low-loss lithium niobate nonlinear photonic devices.

中文翻译：

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通过优化 x 切 LNOI 脊形波导中的铁电畴结构实现高效非线性频率转换


基于薄膜铌酸锂铁电域工程的光子器件是经典信息处理和量子信息处理的关键组件。脊形波导的周期性极化可以避免铌酸锂的选择性刻蚀效应，但高质量铁电畴的制备仍然是一个挑战。在这项工作中，我们优化了施加的电场分布，在脊形波导中获得了矩形倒域结构，这有利于高效的非线性频率转换。使用二次谐波共焦显微镜、压响应力显微镜和化学选择性蚀刻来表征脊形波导中的反转域。此外，通过二次谐波产生研究了周期性极化纳米波导的非线性频率转换性能，测得归一化转换效率为1,720%W−1cm−2，接近于周期极化纳米波导的60%。理论值。这项工作中描述的制造技术将为高效、低损耗铌酸锂非线性光子器件的开发铺平道路。