超高宽深比结构氮化硅波导具有低损耗和高偏振消光比的优异性能, 是抑制集成光学陀螺中偏振噪声的可行性方案。文章基于FEM和FDTD方法对氮化硅波导的模场分布、弯曲损耗及光纤插入损耗进行了仿真分析, 通过对波导截面结构的设计优化, 并采用LPCVD和RIE微纳工艺在石英基底上成功制备了宽深比高达100的单模氮化硅波导。表征及通光测试验证了工艺可行性, 对一长为12mm的氮化硅直波导测试得偏振消光比达3dB。研究结果对超高宽深比氮化硅波导在集成光学陀螺及相关偏振器件中的应用研究具有一定意义。

The ultra high-aspect-ratio silicon nitride waveguide has the excellent performance of low loss and high polarization extinction ratio, and it is a feasible scheme to suppress the polarization noise in integrated optical gyroscope. In this paper, the mode field distribution, bending loss and fiber insertion loss of silicon nitride waveguide have been simulated and analyzed based on FEM and FDTD method. By optimizing the waveguide cross-section structures and using the micro-nano techniques of LPCVD and RIE, the single-mode silicon nitride waveguide with an aspect ratio of high to 100 has been successfully fabricated. The processes feasibility has been verified through characterizations and optical testing. The measured polarization extinction ratio of a 12mm silicon nitride direct waveguide was up to be 3dB. The results of this research have some significance for the application of ultra high-aspect-ratio silicon nitride waveguides in the integrated optical gyroscope and related polarizing devices.