Vertical polarization beam splitter using a hybrid long-range surface plasmon polariton waveguide

A vertical polarization beam splitter using a hybrid long-range surface plasmon polariton (LR-SPP) waveguide is proposed for three-dimensional integration of silicon photonic circuits in a chip. The device is based on a three-port directional coupler that is operated based on mode coupling theory. The hybrid LR-SPP waveguide as the central waveguide in a three-port directional coupler plays a key role in transferring the transverse-magnetic (TM)-polarization mode from the input port to the cross port, which is configured with horizontal and vertical offsets. A 9.7 μm-long vertical polarization splitter with an extinction ratio of 30 dB in the C-band is achieved. The effects of dimensional tolerances are also investigated. The vertical polarization splitter is highly compatible with a complementary metal–oxide–semiconductor (CMOS) fabrication process based on the silicon-on-insulator (SOI) platform.