Chang Ken-Wei, Huang Chia-Chien
Department of Physics, National Chung Hsing University, 250, Kuo Kuang Rd. Taichung, 402, Taiwan, R.O.C.
Institute of Nanoscience, National Chung Hsing University, 250, Kuo Kuang Rd. Taichung, 402, Taiwan, R.O.C.
Sci Rep. 2016 Jan 20;6:19609. doi: 10.1038/srep19609.
We propose an ultracompact broadband polarization beam splitter (PBS) based on a combined hybrid plasmonic waveguide (HPW). The proposed PBS separates transverse-electric (TE) and transverse-magnetic (TM) modes using a bent lower HPW with vertical nanoscale gaps and a straight upper HPW with a horizontal nanoscale gap, respectively, without relying on an additional coupling region. This design considerably reduces the length of the PBS to the submicron scale (920 nm, the shortest PBS reported to date) while offering polarization extinction ratios (PERs) of 19 dB (18 dB) and insertion losses (ILs) of 0.6 dB (0.3 dB) for the TE (TM) mode over an extremely broad band of 400 nm (from λ = 1300 nm to 1700 nm, covering entirely second and third telecom windows). The length of the designed PBS can be reduced further to 620 nm while still offering PERs of 15 dB, realizing a densely photonic integrated circuit. Considering the fabrication tolerance, the designed PBS allows for large geometrical deviations of ± 20 nm while restricting PER variations to within 1 dB, except for those in the nanoscale gaps smaller than 10nm. Additionally, we also address the input and ouput coupling efficiencies of the proposed PBS.
我们提出了一种基于组合式混合等离子体波导（HPW）的超紧凑型宽带偏振分束器（PBS）。所提出的PBS分别使用具有垂直纳米级间隙的弯曲下部HPW和具有水平纳米级间隙的直上部HPW来分离横电（TE）模和横磁（TM）模，而无需依赖额外的耦合区域。这种设计将PBS的长度大幅减小至亚微米尺度（920 nm，是迄今为止报道的最短PBS），同时在400 nm的极宽带宽（从λ = 1300 nm到1700 nm，完全覆盖第二和第三电信窗口）内，对于TE（TM）模提供约19 dB（约18 dB）的偏振消光比（PER）和约0.6 dB（约0.3 dB）的插入损耗（IL）。设计的PBS长度可进一步减小至620 nm，同时仍提供15 dB的PER，实现密集光子集成电路。考虑到制造公差，设计的PBS允许± 20 nm的大几何偏差，同时将PER变化限制在1 dB以内，小于10nm的纳米级间隙除外。此外，我们还讨论了所提出的PBS的输入和输出耦合效率。
