Opt Lett. 2019 Mar 15;44(6):1335-1338. doi: 10.1364/OL.44.001335.
A novel compact polarization beam splitter (PBS) based on a silicon nitride-silica-silicon horizontal slot waveguide is numerically proposed, to the best of our knowledge. In the slot waveguide, the transverse electric (TE) mode propagates through the silicon layer, while the transverse magnetic (TM) mode is confined in the slot region. By utilizing an asymmetric directional coupler (DC) and bent directional coupler (bent DC) consisting of a slot waveguide and a thin silicon waveguide, PBSs with 14.6 μm (DC) and 5.2 μm (bent DC) coupling regions are obtained. Without cascading other structures, the DC PBS shows a low insertion loss (IL) of 0.4 (0.2) dB and high extinction ratio (ER) of 31.56 (24.61) dB for a TE (TM) port around 1.55 μm, while the IL and ER of the bent DC PBS are 0.4 (0.15) dB and 35.83 (21.74) dB, respectively. The proposed PBSs also have a good fabrication tolerance and broad bandwidth (>40 nm) for an ER of >20 dB.
我们首次提出了一种基于氮化硅-二氧化硅-硅水平槽波导的新型紧凑型偏振分束器（PBS）。在槽波导中，横电（TE）模式通过硅层传播，而横磁（TM）模式则被限制在槽区中。通过利用由槽波导和薄硅波导组成的非对称定向耦合器（DC）和弯曲定向耦合器（bent DC），我们获得了具有 14.6μm（DC）和 5.2μm（bent DC）耦合区的 PBS。无需级联其他结构，DC PBS 在 1.55μm 左右的 TE（TM）端口处表现出低插入损耗（IL）为 0.4（0.2）dB 和高消光比（ER）为 31.56（24.61）dB，而 bent DC PBS 的 IL 和 ER 分别为 0.4（0.15）dB 和 35.83（21.74）dB。所提出的 PBS 还具有良好的制造公差和较宽的带宽（>40nm），消光比>20dB。
