基于双层氮化硅减反射垂直光栅耦合器  

Vertical Grating Coupler Based on Double-Layer Silicon Nitride Antireflection

作　　者：吉喆 李东 付士儒 严英占 贾大功[3] Ji Zhe;Li Dong;Fu Shiru;Yan Yingzhan;Jia Dagong(Hebei Key Laboratory of Mechanical Power and Transmission Control,School of Mechanical Engineering,Shijiazhuang Tiedao University,Shijiazhuang 050043,Hebei,China;Information Science Academy of China Electronics Technology Group Corporation,Beijing 100041,China;Key Laboratory of Opto-Electronics Information Technology,Ministry of Education,School of Precision Instrument and Opto-Electronics Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]石家庄铁道大学机械工程学院,河北省工程机械动力与传动控制重点实验室,河北石家庄050043 [2]中国电子科技集团公司信息科学研究院,北京100041 [3]天津大学精密仪器与光电子工程学院,光电信息科学与技术教育部重点实验室,天津300072

出　　处：《光学学报》2024年第2期282-291,共10页Acta Optica Sinica

基　　金：国家自然基金面上项目(61875152);河北省教育厅重点基金(ZD2022106);河北省科技研发平台建设专项(21567622H)。

摘　　要：针对传统光栅耦合器在耦合过程中需要入射光倾斜一定角度且耦合效率低的缺点,提出了一种双层Si_(3)N_(4)减反射垂直光栅耦合器结构。基于时域有限差分法,对双层Si_(3)N_(4)薄膜结构的上、下层Si_(3)N_(4)厚度,下层Si_(3)N_(4)与光栅的距离及上、下层Si_(3)N_(4)之间的高度进行了详细讨论。分析结果表明,对于双层Si_(3)N_(4)减反射垂直光栅耦合器结构,横电波(TE)模式下在1550 nm波长处可以获得超过94%(-0.26 d B)的垂直耦合效率,3 d B带宽为107 nm(1485~1592 nm),具有良好的低损耗特性和带宽特性。同时,在现有加工工艺基础上,对该器件进行了容差分析。分析得知,当光纤光栅对准容差在-1.92~1.92μm范围内、对准角度容差在-1.8°~1.8°范围内时,双层Si_(3)N_(4)减反射垂直光栅耦合器可以获得超过80%的耦合效率。Objective In on-chip communication,the size differences between single-mode fibers and on-chip optical waveguides will cause a mode mismatch.Due to the grating diffraction,the grating coupler can avoid the above problems,and thus it has become an ideal device for connecting the external light source with the on-chip photon device.Traditional grating couplers generally employ a tilt angle of 8°–12°to avoid second-order reflection,but the fiber has to be adjusted and polished before the silicon photonic integrated chip is tested and packaged,which results in high testing and packaging costs and is not conducive to fast wafer level testing and low-cost photon packaging.With the fiber grating placed vertically,the light emitted by the light source is vertically incident on the grating,whose advantages are as follows:it is unnecessary for tilting the fiber top and adjusting the angle,with reduced fiber alignment difficulty,applicability for more intensive integration,and more cost-effectiveness than traditional grating couplers.We design a double-layer Si_(3)N_(4) antireflection vertical grating coupler structure that can be employed in wavelength division multiplexing technology.This vertical grating coupler shows excellent characteristics of low loss and broad bandwidth,and the feasibility of processing and application of the device is proven by analysis.Our results can provide ideas for vertical coupling applications and low-cost optical fiber packaging of silicon photonic integrated chips.Methods A double-layer Si_(3)N_(4) antireflection vertical grating coupler is designed.First,the model is built based on the finite difference time domain method,and the three initial structural parameters of the grating(grating period,duty cycle,and etching depth)are optimized by particle swarm optimization to obtain the maximum coupling efficiency.After obtaining the optimal parameters,the appropriate grating period,duty cycle,and etching depth are analyzed and selected according to the practical application requirements.Th

关 键 词：垂直光栅耦合器 Si_(3)N_(4)薄膜 减反射 耦合效率 

分 类 号：TN256[电子电信—物理电子学]