利用飞秒激光直写制备高品质晶体微腔及非线性光学研究

High-Q whispering-gallery-mode (WGM) microresonators can efficiently confine light in a very small volume via total internal reflection at the smooth boundary, leading to enhancement of interaction of light with matter. High-Q WGM microresonators have been extensively used in a wide range of applications, such as low threshold nonlinear optics, quantum electrodynamics, optomechanics and biosensing. In particular, due to their high nonlinear optical coefficients (second order or third order), low intrinsic absorption loss, and large transparent windows, crystalline resonators have recently attracted significant attention for nonlinear optical applications. However, realization of on-chip high-Q sub-millimeter crystalline resonators for construction of next generation quantum information processing chip remains a challenge. This project will focus on the fabrication of high-Q microresonators on dielectric crystalline chip by femtosecond micromachining, which provides a key technique for fabricating high-Q microresonators in a variety of dielectric crystals. In addition, nonlinear optical processes such as second harmonic generation, down conversion, and four wave frequency mixing will be investigated using the fabricated microresonators, with the main focus placed on improvement of phase matching.

高品质(Q)的回音壁模式光学微腔通过全内反射有效地把光子约束在很小的体积里，显著地增强光与物质的相互作用，在低阈值的非线性光学、量子电动力学、光机械力学和生物传感等领域有广泛的应用。对于非线性光学应用，介质晶体谐振腔具有高非线性系数、宽透明窗口、低本征吸收等独特优点，然而微米尺度的晶体微腔的制备至今仍很非常困难。本课题旨在发展一种基于介质晶体的光学微腔的飞秒激光加工技术，解决在多种介质晶体材料上构建高品质光学微腔的关键技术问题；在此基础上，通过实现相位匹配或准相位匹配，提升非线性光学，如倍频、下转换、四波混频等效应的转换效率。

高品质(Q)的回音壁模式光学微腔通过全内反射实现对光子在时间上和空间上的约束。这种约束强烈增强光与物质的相互作用，在非线性光学、量子电动力学、光子学、片上量子信息处理等领域有广泛的应用。而光学晶体，特别是铌酸锂，具有高非线性系数、宽透明窗口、低本征吸收、大的电光系数等特性。晶体光学微腔结合了晶体与微腔各自的优点，在非线性光学转换、片上量子信息处理具有潜在的重要价值。然而由于晶体耐腐蚀，高品质的晶体微腔难以制备。基于上述研究背景，本项目开发了一种基于飞秒激光光刻、化学机械抛光去除铌酸锂的成套技术方案，解决了超高品质铌酸锂微腔制备、多功能集成的关键技术问题；在此基础上，通过发展新的相位匹配技术，提升微腔非线性光学转换的转换效率。