Tunable polarization splitter based on dual-channel waveguide

Abstract

In this work, a compact and tunable polarization splitter is introduced and numerically investigated. The suggested design is based on a dual-channel silica-on-silicon waveguide, where one channel is infiltrated with nematic liquid crystal (NLC) material, while the other channel is filled with BK7 glass. The NLC temperature controls the phase-matching wavelength at which strong coupling between the two cores occurs. Moreover, the splitting function can be switched between the two fundamental polarizations, i.e., transverse electric (TE) and transverse magnetic (TM), by rotating the NLC molecules via an external electric field. The full-vectorial finite difference method is used to study the modal and coupling characteristics of the splitter. The simulation results show that the proposed device offers a strong wavelength tunability and selectivity, with a short device length of 207 µm at the telecommunication wavelength of 1.3 μm. It also provides a wide bandwidth of 66 nm with crosstalk below -20 dB, ensuring the device’s superior performance.