A compact, broadband slot waveguide polarization rotator

We demonstrate a chip-scale compact, broadband polarization rotator on a silicon substrate. Unlike previously demonstrated waveguide polarization rotators, our approach relies on the adiabatic mode evolution in a single horizontal slot-waveguide, which results in a simple design and one-mask fabrication process.The structure is designed to rotate the TM-polarized input by 90 degree while be transparent with the TE-polarized input. The fabricated device has a total length of 100μm. Transmission spectra show the average polarization extinction ratios of 20 dB and 15 dB for TE and TM -polarized inputs, respectively.