Fig. 1. Schematic diagram of multifunctional polarizer. (a) 3D structure of polarizer; (b), (c) cross-section view in xz plane of triple-waveguide coupler and polarization control regions. Correspondence of input-output and GSST phase states is also listed in figure

Fig. 2. Electric field distribution of dominant components for supermodes in a triple-waveguide coupler at 1550 nm wavelength. (a), (b), (c) The 1st symmetric, 2nd symmetric, and antisymmetric supermodes for TM polarization, respectively; (d), (e) the even and odd modes for TE polarization respectively

Fig. 3. Effect of α-Si geometric parameters on coupling. (a) Variations of geometric parameters of α-Si satisfying phase-matching condition; (b) coupling length of TM mode L_TM and ratio of coupling length L_TE/L_TM as functions of width of α-Si W_Si

Fig. 4. Effect of length of GSST L_PE on performance of polarizer. (a) TE mode; (b) TM mode

Fig. 5. Simulated propagation of electric field of device at wavelength of 1550 nm. (a) TE mode (amorphous); (b) TE mode (crystalline); (c) TM mode (amorphous); (d) TM mode (crystalline)

Fig. 6. Performance of device at wavelengths from 1530 to 1580 nm. (a) TE mode; (b) TM mode

Fig. 7. Variations of PER and IL in different fabrication tolerance. (a), (d) Deviation between waveguide gap δG; (b), (e)α-Sinanostrip central position deviationδY; (c), (f) thickness deviation of GSST δH_PE and δH_PM