High-Performance Silicon Polarization Beam Splitter Assisted by the Sub-Wavelength Structures

A high-performance polarization beam splitter(PBS) is proposed and experimentally demonstrated on the220-nm silicon-on-insulator (SOI) platform. The proposed PBSconsists of a sub-wavelength grating (SWG) assisted adiabaticdirectional coupler (ADC) and a simple filter at the throughport of the ADC. The SWG structures embedded in the ADCcan suppress and enhance the optical field evolutions of thefundamental TE and TM modes (referred to as TE and TMmodes in short), respectively, thus enhancing the separation ofthese two modes. The simple filter composed of four Euler bendsis used to further improve the polarization extinction ratio (PER)of the TM mode while maintaining low insertion loss (IL) forthe TE mode. The simulated results show that our proposedPBS possesses the high performance of IL<0.3 dB and PER>30 dB for both the TE and TM modes over the bandwidthof 1.46-1.625 mu m, which covers the most important S, C, and,L bands for optical communications. The experimental resultsshow that the fabricated PBS has excellent performance of IL<0.8 dB and PER>24.5 dB over the bandwidth of 1.53-1.61 mu m