An Ultracompact Polarization-Insensitive Silicon-Based Strip-to-Slot Power Splitter

An ultracompact and polarization-insensitive silicon-based strip-to-slot power splitter based on multimode interference is proposed, where an inverse-tapered subwavelength grating (SWG) structure is embedded in the center of the multimode waveguide and two strip-to-slot mode converters are integrated at the end. With the optimized SWG structure, the length of the multimode waveguide is reduced by nearly half against without such a structure and polarization-insensitive transmission can be achieved. Tapered and cut-right-angled waveguides are also introduced to enhance the performance. Simulation results show that a length of 1.92 μm for the multimode region with an insertion loss of 0.39 dB (polarization-dependent loss (PDL) = 0), the reflection losses of -30.51 dB (transverse-electric mode) and -33.62 dB (transverse-magnetic mode) are obtained at 1.55 μm, and the bandwidth can be enlarged to ~105 nm for a PDL <; 0.1 dB. In addition, fabrication tolerances and mode-field evolution are also presented.