薄膜铌酸锂低串扰交叉波导  

Low⁃Crosstalk Crossing Waveguide with Thin⁃Film Lithium Niobate(Invited)

作　　者：胡毅标 何佳晶 王俊 Hu Yibiao;He Jiajing;Wang Jun(School of Physical Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China;Qiguang Research and Innovation Center,Aerospace Laser Technology and System Department,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学技术大学物理学院,安徽合肥230026 [2]中国科学院上海光学精密机械研究所空天激光技术与系统部启光创新中心,上海201800 [3]中国科学院大学材料科学与光电工程中心,北京100049

出　　处：《中国激光》2024年第14期255-263,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(62305354);上海扬帆计划(23YF1454100)。

摘　　要：随着绝缘体上铌酸锂(LNOI)平台集成器件的增加,实现大规模集成变得尤为重要。低串扰和低损耗的多通道交叉波导可以大大减少波导连接的面积,从而提高集成密度和路由的灵活性。利用铌酸锂的各向异性,设计了基于自成像原理的不同尺寸的2×2交叉波导。该交叉波导基于X切LNOI,制造出的器件在C波段的串扰分别小于-33.31 dB(Y传方向)和-30.81 dB(Z传方向),插入损耗最小分别为0.094 dB(Y传方向)和0.356 dB(Z传方向)。Objective With breakthroughs in fabrication techniques,integrated optical components have been developed on a lithium niobate on insulator (LNOI) platform with unprecedented performance.However,with the requirement for large-scale integration of devices on the LNOI platform,multimode crossing waveguides,which have low crosstalk and loss,are essential to enhance integration density and routing flexibility.Because of the anisotropic characteristics of lithium niobate,the design of crossing waveguides must consider the different refractive indices in different propagation directions.In this work,we propose and demonstrate a 2×2 crossing waveguide based on self-imaging theory under different waveguide sizes in the X-cutting Y-propagating and X-cutting Z-propagating directions to satisfy practical requirements.Methods This study employs self-imaging theory to design the crossing waveguide.First,the relationship between the lithiumniobate waveguide width and effective refractive index is obtained by simulation,and the optimal beat length is calculated using the self-imaging principle.Subsequently,the calculated parameters are introduced into the software as initial values.In this process,the structural parameters of the multimode waveguide in both directions are set to be the same,and the optimal values are found by parameter scanning.The structural parameters in one direction are fixed as previously described,and those in the other directions are scanned to find the best structural parameters.Finally,a simulated crossing waveguide is fabricated and measured.The LNOI wafers are cut into 25 mm×21 mm pieces.All pieces are cleaned with a piranha solution.Hydrogen silsesquioxane (HSQ) resist is then spincoated onto the samples.The HSQ resist is exposed by electron beam lithography and subsequently developed.The patterns are then transferred to the LNOI device layer via reactive-ion etching,where the etching depth of the LNOI layer is 300 nm.Finally,a 500-nm-thick SiO_(2) layer is formed on the lithium niobate waveguide t

关 键 词：交叉波导 铌酸锂 集成光子 自成像 

分 类 号：O436[机械工程—光学工程]