An ultra-compact broadband polarizing beam splitter utilizing hybrid plasmonic waveguide

Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems. In this paper, we present an asymmetric polarizing beam splitter utilizing hybrid plasmonic waveguide. The special hybrid structure with a hybrid waveguide and a dielectric waveguide can limit the energy of TE and TM modes to a different layer. Therefore, we can achieve beam splitting by adjusting the corresponding parameters of the two waveguides. First, we studied the influences of different structure parameters on the real part of the effective mode refractive index of the two waveguides, and obtained a set of parameters that satisfy the condition of strong coupling of TM mode and weak coupling of TE mode. Then, the performance of our proposed polarizing beam splitter is evaluated numerically. The length of the coupling section is only 4.1 µm, and the propagation loss of TM and TE modes is 0.0025 dB/µm and 0.0031 dB/µm respectively. Additionally, the extinction ratios of TM and TE modes are 10.62 dB and 12.55 dB, respectively. Particularly, the proposed device has excellent wavelength insensitivity. Over the entire C-band, the fluctuation of the whole normalized output power is less than 0.03. In short, our proposed asymmetric polarizing beam splitter features ultra-compactness, low propagation loss, and broad bandwidth, which would provide promising applications in polarization multiplexing system and polarization diversity circuits relevant to optical interconnection.