Ni Bin, Xiao Jinbiao
Appl Opt. 2018 May 20;57(15):4032-4038. doi: 10.1364/AO.57.004032.
A compact TE-pass polarizer for silicon-based slot waveguides is numerically proposed based on a directional coupler where an asymmetrical slot waveguide (ASW) and hybrid plasmonic waveguide (HPW) are involved. The input section is linearly tapered to an ASW to markedly enlarge the modal birefringence. Beneficially, only the TM mode can be coupled into the adjacent HPW and attenuated while the injected TE mode just passes through the slot waveguide without coupling by properly choosing the dimensions. As a consequence, an efficient TE-pass polarizer can be implemented. From the simulation results, the proposed polarizer has an extinction ratio (ER) of 45 dB and insertion loss (IL) of 0.44 dB at 1.55 μm, and its bandwidth exceeds 130 nm with the ER>30 dB and IL<1 dB. In addition, fabrication tolerances to the key structural parameters are analyzed and field evolution along the propagation distance is also demonstrated.
基于一种涉及非对称槽波导（ASW）和混合等离子体波导（HPW）的定向耦合器，数值提出了一种用于硅基槽波导的紧凑型TE模式偏振器。输入部分线性渐变为ASW，以显著增大模式双折射。有利的是，通过适当选择尺寸，只有TM模式可以耦合到相邻的HPW中并被衰减，而注入的TE模式则直接通过槽波导而不发生耦合。因此，可以实现一种高效的TE模式偏振器。从仿真结果来看，所提出的偏振器在1.55μm波长处的消光比（ER）为45dB，插入损耗（IL）为0.44dB，其带宽超过130nm，消光比大于30dB且插入损耗小于1dB。此外，还分析了关键结构参数的制造公差，并展示了沿传播距离的场演变情况。
