Design of Polarization Rotator Based on Asymmetric Slot-Waveguide

In this study, a slot-waveguide based polarization rotator (PR) is proposed and designed on silicon-on-isulator platform. Since the entire structure is symetrically distributed along the y = x axis, the optical axies of the excited modes are rotated by 45° with respect to the x-axis, which leads to a high polarization conversion efficiency. Simulation results using 3D-FDTD method illustrate that a polarization conversion efficiency of 99.7% is obtained with a device length of only 8 μm at wavelength of 1.55 μm. The corresponding extinction ratio is - 25.9dB and insertion loss is 1.19dB. Additionally, the wavelength dependence of the proposed PR is also discussed in detail.