The management of polarization state is crucial for silicon photonics, however, it is often compromised by weak light-matter interactions, leading to the need for extending footprints of on-chip devices and huge power cost. In this paper, we propose a tunable silicon photonic polarizer designed to separate and manipulate polarization states based on selective silicon asymmetric directional couplers (ADCs) assisted with phase change material (PCM)[4]. The proposed polarizer includes a polarized beam splitter, a TE mode selective ADC assisted with PCM, a TM mode selective ADC assisted with PCM and a polarized light combiner. By tuning the GST of the TE/TM light selective ADC into crystalline state, phase matching occurs in the directional coupler between the hybrid waveguide and the bus waveguide, then the TE/TM modes can be efficiently excluded from the polarizer. On the other hand, by tuning the GST of the TE/TM light selective ADC into amorphous state, there is a phase mismatch between the hybrid waveguide and the bus waveguide, then the TE/TM light can pass through the bus waveguide and output from the polarized beam combiner. Simulation results indicate that this selective silicon photonic polarizer has a high extinction ratio over 37 dB for the TM mode and over 31 dB for the TE mode, with a minimal insertion loss of 1.2 dB for the input light.
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