飞秒激光直写低损耗铌酸锂体三维波导微结构及其全光调控的应用基础研究

Due to its excellent linear and nonlinear optical properties, Lithium niobite (LiNbO3) crystal is one of the ideal materials for fabricating integrated photonic chips, while functionalized LiNbO3 optical waveguide is one of the most foundational units in building these photonic chips. In this project, we will study on the fabrication, nonlinear effects, and optical control properties of novel integrated photonic unit basing on femtosecond direct writing low-loss 3D LiNbO3 waveguides. The main contents of this project include: (1) the physical mechanism and the fabrication of low-loss, deeply buried type II LiNbO3 waveguides direct written with femtosecond lasers; (2) design, nonlinear optical effects and novel optical manipulation mechanism in the 3D LiNbO3 waveguides for high efficient all-optical control; (3) fabrication, optical manipulation properties and applications of the high efficient optical control 3D LiNbO3 waveguides. The study will benefit the development of the technique to fabricate micro/nano photonic structures and devices in LiNbO3 crystal, increase the integration of the integrated photonic chips. It will improve the understanding on the nonlinear optical effects and physics laws in LiNbO3 photonic micro structures for expanding their multi-fields control functionality, and thus propel the applications of LiNbO3 micro/nano optical devices in integrated optics, all-optical communication and quantum optics information process etc.

铌酸锂晶体具有优良的线性和非线性光学性能，是构建集成光子学芯片理想的基础材料之一，而功能化的铌酸锂光波导是集成光子学芯片之中最基本的结构单元。本项目中，我们将开展以飞秒激光直写低损耗铌酸锂体三维波导为基础的新型高效全光调控集成光子学微结构的制备、非线性光学效应和全光主动调控应用的研究，具体研究内容包括：（1）飞秒激光直写铌酸锂II型波导的微观机制与低损耗、深埋层铌酸锂波导的制备；（2）高效全光调控铌酸锂三维波导微结构的设计、非线性光学效应与新型光调控机理；（3）高效光调控铌酸锂三维波导器件的制备、性能与应用研究。该研究将推动铌酸锂晶体微纳光子学结构与器件的制备技术的发展，提升铌酸锂集成光子学芯片的集成维度，增进对铌酸锂光子学微结构中的非线性光学效应和物理规律的理解，拓展铌酸锂光子学微结构的多场调控新功能，促进铌酸锂微纳光学器件在集成光学、全光通讯和量子光学信息处理等领域的应用。

铌酸锂晶体是构建集成光子学芯片最理想的衬底材料之一，铌酸锂光子学微结构与功能器件是实现多功能集成光子学芯片的关键核心要素。在本项目支持下，课题团队聚焦高品质铌酸锂集成光子学微结构加工与器件研发，开展了较为系统的理论和实验研究。我们完成了高重频近红外超快激光直写加工系统的构建，优化完善了针对绝缘体上铌酸锂薄膜材料光子学微结构精密加工的飞秒激光光刻辅助化学机械抛光技术工艺，显著提升了铌酸锂片上集成光子学微结构的性能，实现了接近铌酸锂晶体材料本征吸收极限的超低损耗光波导和超高品质因子微腔结构的制备，发展了提升片上集成铌酸锂光波导与光纤等片外光子学微结构耦合效率的新途径。基于飞秒激光光刻辅助化学机械抛光技术和铌酸锂薄膜材料，我们研制了波导分束器、耦合双谐振腔、多功能电调控光子芯片、电光调制微腔光频梳器件、低功耗宽带电光调制器、高增益波导光放大器、单模激光器和窄线宽单频激光器等一系列有源无源铌酸锂片上集成光子器件，并观测到了多边形光学共振模式、高效频率转换等非线性光学效应。相关研究成果有力的推动了高性能铌酸锂片上集成光子器件的研发和实用化铌酸锂光子芯片的研制。此外，我们还探索了高重频超快激光三维内雕加工工艺，并研发了若干可电调控的微流控结构器件，为进一步发展基于超快激光微纳加工技术的多功能器件制备工艺提供了重要技术支撑。