On-chip polarization splitter based on a multimode plasmonic waveguide
The miniaturization of polarization beam splitters (PBSs) is vital for ultradense chip-scale photonic integrated circuits. However, the small PBSs based on complex hybrid plasmonic structures exhibit large fabrication difficulties or high insertion losses. Here, by designing a bending multimode plasmonic waveguide, an ultrabroadband on-chip plasmonic PBS with low insertion losses is numerically and experimentally realized. The multimode plasmonic waveguide, consisting of a metal strip with a V-shaped groove on the metal surface, supports the symmetric and antisymmetric surface plasmon polariton (SPP) waveguide modes in nature. Due to the different field confinements of the two SPP waveguide modes, which result in different bending losses, the two incident SPP waveguide modes of orthogonal polarization states are efficiently split in the bending multimode plasmonic waveguide. The numerical simulations show that the operation bandwidth of the proposed PBS is as large as 430 nm because there is no resonance or interference effect in the splitting process. Compared with the complex hybrid plasmonic structure, the simple bending multimode plasmonic waveguide is much easier to fabricate. In the experiment, a broadband (Δλ≈120 nm) and low-insertion-loss (<3 dB with a minimum insertion loss of 0.7 dB) PBS is demonstrated by using the strongly confined waveguide modes as the incident sources in the bending multimode plasmonic waveguide.
基金项目：National Natural Science Foundation of China (NSFC)10.13039/501100001809 (11674014, 61475005, 11527901, 11134001); National Basic Research Program of China (2016YFA0203500, 2013CB328704).
Chengwei Sun：State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Department of Physics, Peking University, Beijing 100871, China
Hongyun Li：State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Department of Physics, Peking University, Beijing 100871, China
Qihuang Gong：State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Department of Physics, Peking University, Beijing 100871, ChinaCollaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
Jianjun Chen：State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Department of Physics, Peking University, Beijing 100871, ChinaCollaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
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Fengyuan Gan, Chengwei Sun, Hongyun Li, Qihuang Gong, and Jianjun Chen, "On-chip polarization splitter based on a multimode plasmonic waveguide," Photonics Research 6(1), 47 (2018)