Ultra-short silicon-on-insulator (SOI) polarization rotator between a slot and a strip waveguide based on a nonlinear...

A design of ultra-short integrated polarization rotator (PR) with nonlinear and flat-tip tapers is demonstrated theoretically. Based on mode-evolution theory and three-dimensional (3D) finite-difference time-domain (FDTD) simulation, raised cosine profiled tapers are introduced and optimized in the transition region, which improve the polarized modes coupling and decrease the conversion length to 6 μm for the wavelength of 1.55 μm. Numerical simulations obtain extinction ratio of 32 dB and loss of 0.14 dB with practical material parameters. The method and result presented here can be extremely valuable for applications in polarization diversity circuits.