Compact silicon slot waveguide polarization splitter

Abstract

A compact slot waveguide polarization splitter based on the silicon (Si) material system is proposed and analyzed. The slot waveguide structure introduces significant beat-length differences for transverse electric and transverse magnetic polarizations at operation wavelength of 1.55 µm. The special self-imaging design with limited modes and weak second-mode excitation shortens the device length to <50 µm, while still delivering good performance. The polarization extinction ratio is 13 dB, and the excess loss is only 0.3 dB. The splitter also has a relaxed length tolerance of 550 nm. These attributes make it an excellent candidate for polarization diversity circuits and compact electronic-photonic integrated circuits.