硅基片上偏振分束器研究进展

硅基集成光波导具有很高的折射率对比度，能将光场限制在纳米尺度，是制备结构紧凑、高效的纳米光子器件的关键。但是，高折射率对比度也会引起波导双折射效应。因此，几乎所有纳米光子器件都是偏振相关的。偏振分束器是偏振分集光子集成电路中克服硅纳米器件强偏振依赖性的重要组成部分，在片上相干通信、传感与环境检测等领域具有广阔的应用前景。目前报道的基于亚波长光栅波导结构的偏振分束器，工作带宽在200 nm以上，消光比也超过了20 dB。文章简述了各种类型偏振分束器的工作原理，对其尺寸、消光比、带宽等方面的性能进行了比较，分析了各类偏振分束器的优劣势，最后总结了其主要应用场景并展望了未来发展方向。

Silicon Based On-chip Polarization Beam Splitters

Silicon photonic waveguides, exhibiting high refractive index contrast and nano-scale optical field, are capable to producing compact and efficient nanophotonic devices. However, birefringence is inevitable for high refractive index contrast waveguides, and thus almost all nanophotonic devices are polarization sensitive. Polarizing beam splitter (PBS) is an important component to overcome the strong polarization dependence of silicon nanodevices in polarization diversity photonic integrated circuits, and has received much attention in recent years. The recently reported sophisticated subwavelength grating waveguide (SWG) based PBS has a working bandwidth of more than 200nm and an extinction ratio of more than 20dB. In this paper, the working principles of various types of PBSs are briefly deswoedcribed, and their performances in terms of size, extinction ratio and bandwidth are illustrated, and the advantages and disadvantages are also analyzed. Finally, the application scenarios and future development of PBS are summarized and prospected.