基于栅型光波导的自由空间光耦合性能研究

Optical Coupling Performance in Free Space Based on Grating-Type Optical Waveguide

针对大气湍流信道中空间光耦合效率低、对准难度大的问题,提出一种将湍流信号光束通过光栅结构耦合进光波导的研究方案,在修正的Von Karman湍流谱模型下,分析大气湍流对空间光与栅型光波导耦合参数的影响,通过优化光栅结构参数,设计高效空间光耦合波导芯片。此外,引入三组Si/SiO_(2)反射镜结构,减少向下耦合损耗,进一步提高光栅耦合效率。仿真结果表明,对于受大气湍流影响的空间光,当光栅周期为660 nm,刻蚀深度为100 nm,下包层厚度为1.45μm时,该入射光栅耦合器在1550 nm波长处的耦合效率为74%(无反射镜时,耦合效率为50.5%),实现了大气湍流环境中空间光的高效耦合,对提升通信效率和自由空间光通信领域的光电集成化具有重要的意义。

Spatial optical couplings in atmospheric turbulence channels are associated with low efficiencies and difficult alignments,hence,in this study,a research scheme for coupling a turbulent signal beam into optical waveguides through a grating was proposed and the influence of atmospheric turbulence on spatial light and optical waveguide coupling parameters was analyzed.Moreover,a highly efficient spatial optical coupling waveguide chip was designed by optimizing the structural parameters of the grating.Additionally,three sets of Si/SiO_(2) mirrors were introduced to reduce the downward coupling loss and further improve the grating coupling efficiency.Simulation results show that for the spatial light affected by atmospheric turbulence,the coupling efficiency of the incident grating coupler at 1550 nm was 74%(50.5%,without adding the mirrors)when the grating period,etching depth,and lower cladding thickness were 660 nm,100 nm,and 1.45μm,respectively,indicating the efficient coupling of spatial light in the atmospheric turbulent channels.The findings of this study will be of great significance in improving the communication efficiency and photoelectric integration in the field of freespace optical communication.