Fig. 1. Schematic of the proposed non-volatile polarization-insensitive silicon-based 1×2 optical mode switch using phase-change materials

Fig. 2. Proposed polarization beam splitter/combiner. (a) Schematic of structure; (b) cross-sectional view

Fig. 3. Optimization of structural parameters of proposed polarization beam splitter/combiner. (a) (b) Polarization extinction ratio and insertion loss as a function of the coupling length L (G_s=0.20 µm, W₂=0.30 µm, and h₁=0.23 µm);(c) (d) polarization extinction ratio and insertion loss as a function of the gap G_s (L=6.50 µm, W₂=0.30 µm, and h₁=0.23 µm); (e) (f) polarization extinction ratio and insertion loss as a function of the width W₂ (L=6.50 µm, G_s=0.20 µm, and h₁=0.23 µm); (g) (h) polarization extinction ratio and insertion loss as a function of the thickness h₁ (L=6.50 µm, G_s=0.20 µm, and W₂=0.30 µm)

Fig. 4. Performance of the desinged polarization beam splitter/combiner. (a) Polarization extinction ratio as a function of the wavelength; (b) insertion loss as a function of the wavelength

Fig. 5. Directional couplers with phase-change materials operating in the TE₀ or TM₀ modes, which are respectively named as DCPCM_TE and DCPCM_TM. (a) (c) Schematics of structures; (b) (d) cross-sectional views

Fig. 6. Coupling efficiency and transmission efficiency of the proposed directional couplers changing with the length L_ge or L_gm. (a) Coupling efficiency and transmission efficiency of DCPCM_TE changing with the length L_ge; (b) coupling efficiency and transmission efficiency of DCPCM_TM_{changing with the length Lgm}

Fig. 7. Transmission spectra of the designed directional couplers. (a) Transmission spectra of DCPCM_TE; (b) transmission spectra of DCPCM_TM

Fig. 8. Schematic of proposed polarization-insensitive silicon-based crossing waveguide structure

Fig. 9. Transmission spectra of designed polarization-insensitive silicon-based crossing waveguide. (a) Transmission spectra when input TE₀ mode; (b) transmission spectra when input TM₀ mode

Fig. 10. Schematics of the proposed mode converters. (a) Schematic of MD_TE; (b) schematic of MD_TM

Fig. 11. Conversion efficiency of the proposed mode converters changing with the length L_e or L_m._{(a) Conversion efficiency of MD_TE changing with the length Le; (b) conversion efficiency of MD_TM changing with the length Lm}

Fig. 12. Conversion efficiency of designed MD_TE and MD_TM changing with the wavelength

Fig. 13. Simulated lightpaths in the designed non-volatile polarization-insensitive silicon-based 1×2 optical mode switch using phase-change materials at a wavelength of 1550 nm. (a) Simulated lightpath in the designed device when the TE₀ mode is input and Ge₂Sb₂Te₅ is in the crystalline state; (b) simulated lightpath in the designed device when the TE₀ mode is input and Ge₂Sb₂Te₅ is in the amorphous state; (c) simulated lightpath in the designed device when the TM₀ mode is input and Ge₂Sb₂Te₅ is in the amorphous state; (d) simulated lightpath in the designed device when the TM₀ mode is input and Ge₂Sb₂Te₅ is in the crystalline state

Fig. 14. Transmission spectra of the designed non-volatile polarization-insensitive silicon-based 1×2 optical mode switch using phase-change materials. (a) Transmission spectra with Ge₂Sb₂Te₅ is in the amorphous state; (b) transmission spectra with Ge₂Sb₂Te₅ is in the crystalline state

Fig. 15. Temperature changing with the time. (a) Temperature changing with the time in the crystallization process of Ge₂Sb₂Te₅;_{(b) temperature changing with the time in the re-amorphization process of Ge2Sb2Te5}

Fig. 16. Insertion loss and crosstalk of the designed non-volatile polarization-insensitive silicon-based 1×2 optical mode switch using phase-change materials changing with ΔW orΔh. (a) Insertion loss changing with ΔW; (b) crosstalk changing with ΔW; (c) insertion loss changing with Δh; (d) crosstalk changing with Δh