Numerical Investigation on Elliptic Cylindrical Nanowire Hybrid Plasmonic Waveguide–Based Polarization Beam Splitter

Abstract

A novel design of elliptic cylindrical nanowire hybrid plasmonic waveguide (ECNHPW)–based polarization beam splitter (PBS) is proposed. In the proposed design, the ECNHPW arm acts as an input port and a bar port; on the other hand, a regular silicon wire (RSW) arm acts as a cross port. By selecting the physical parameters of the proposed PBS accurately, the transverse electric (TE) mode is merely satisfied with the phase-matching condition. In contrast, the transverse magnetic (TM) mode does not propagate to the RSW arm. Consequently, the TM input mode goes directly to the ECNHPW arm, while the TE input mode in ECNHPW is coupled with RSW arm. As a result, the two different polarization modes are meritoriously separated, and they pass through two different arms. For the proposed PBS, the insertion loss (IL) of both polarizations lies below 1 dB. For TE input, the value of the polarization extinction ratio (PER) is 27.2 dB, and for TM input, it is 23.9 dB at 1550 nm operating wavelength. Further optimization is implemented by varying the wavelength, thickness of SiO2, and the gap between the waveguides using the finite element method (FEM). The proposed PBS is designed with 150 nm bandwidth, high PER, and low IL, which can be suitable for photonic integrated circuits (PICs).