Realization of a compact polarization splitter-rotator on silicon.

Abstract

A novel compact polarization splitter-rotator (PSR) is proposed and realized with silicon-on-insulator nanowires. The present PSR consists of an adiabatic taper, an asymmetric directional coupler (ADC), and a multimode interference (MMI) mode filter. The adiabatic taper enables an efficient mode conversion from the launched TM0 mode to the TE1 mode in a wide waveguide, which is then coupled to the TE0 mode of a narrow waveguide through the ADC. Meanwhile, the launched TE0 mode does not have mode conversion and outputs from the through port directly. The MMI mode filter is cascaded at the through port to filter out the residual power of the TE1 mode so that the extinction ratio of the PSR is improved greatly. The total length of the PSR is ∼70 μm and the fabricated PSR has an extinction ratio of ∼20 dB over a broadband ranging from 1547 to 1597nm.