基于三波导定向耦合器的紧凑型偏振分束器的设计  

Design of Compact Polarization Beam Splitter Based on Triple-waveguide Directional Coupler

作　　者：周冬梅[1] 王爱环 李翠然[1] 吴小所[1] 闫保万 ZHOU Dongmei;WANG Aihuan;LI Cuiran;WU Xiaosuo;YAN Baowan(School of Electronic and Information Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学电子与信息工程学院,兰州730070

出　　处：《光子学报》2022年第1期278-287,共10页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.61661025,62161016)。

摘　　要：为了提高偏振分束器的消光比,利用混合等离子体波导和条形介质波导之间的非对称定向耦合特性,设计了由两个尺寸不同的硅波导和一个中间输入混合等离子体波导组成的偏振分束器,采用三维时域有限差分法对偏振分束器的结构和性能进行优化。实验结果表明:混合等离子体波导中TE和TM模式的双折射率对比通过介质加载波导增强,可获得超紧凑的结构,实验耦合长度仅有4.6μm;在1.55μm的中心波长处,TE模式的偏振消光比为-38.9 dB,插入损耗为0.5 dB,TM模式的消光比为-34.7 dB,插入损耗为0.45 dB,设计的偏振分束器具有高消光比;在波导制作公差范围内,模式的插入损耗小于2.8 dB,消光比低于-22.5 dB。In recent years,the silicon-on-insulator platform has attracted much interest in implementing integrated optical circuits. Due to the high refractive index contrast between the waveguide and cladding,the silicon-on-insulator waveguide has a strong light confinement ability,which helps the device to achieve a compact structure size and large-scale integration. However,this high refractive index contrast causes silicon nanophotonic devices to have high polarization sensitivity so that TE and TM modes have different propagation characteristics in an identical silicon-on-insulator waveguide,which may disrupt the optical signals in optical interconnections and quantum communications. To tackle this problem,one solution is using a polarization beam splitter to polarize the TM mode and TE mode light. Considering future ultradense photonic integrated circuits,a compact PBS with high performance is desired. Therefore,the hybrid plasma waveguide is introduced into the design of the polarization beam splitter. The hybrid plasmonic waveguide consists of a high refractive index dielectric layer(e.g.,Si),a metal cap(e.g.,Ag),and a thin low-index material layer(e. g.,SiO2) between the Si layer and the metal layer. Compared with the traditional dielectric waveguide, it has a significant birefringence effect, which can maintain the performance of the device and further reduce the size of the device.In this paper,we propose and optimize a novel hybrid plasmonic polarization beam splitter utilizing asymmetrical directional coupling between the dielectric waveguides and a hybrid plasmonic waveguide on the silicon-on-insulator platform,which is ultracompact, and low-loss. Employing phase-matching conditions and super-mode theory, this polarization beam splitter is elaborately designed. The device is a three-waveguide asymmetric directional coupler. The middle hybrid plasmonic waveguide,which has a dielectric-loaded structure to enhance the refractive index contrast,is defined as the input waveguide. And different silicon-based wavegu

关 键 词：集成光学器件 偏振分束器 时域有限差分法 光波导 消光比 插入损耗 

分 类 号：TN256[电子电信—物理电子学]