Fig. 1. Schematic diagram of grating structure. (a) Fused silica transmission grating; (b) encapsulated grating

Fig. 2. Effective refractive indices of TiO₂ encapsulated grating as a function of filling factor. (a) Effective refractive indices of two polarization modes; (b) difference of effective refractive indices of two polarization modes

Fig. 3. Non-polarized (NP) diffraction efficiency distribution of TiO₂ encapsulated grating at different groove depths and filling factors calculated by FEM

Fig. 4. Diffraction efficiency and polarization sensitivity curve for grating groove depth of 713 nm and filling factor of 0.384.

Fig. 5. Fused silica transmission grating designed by FEM. (a) NP diffraction efficiency distribution at different groove depths and filling factors; (b) diffraction efficiency and polarization sensitivity curve within waveband of fused silica transmission grating

Fig. 6. -1 order diffraction efficiency and polarization sensitivity of encapsulated grating as a function of wavelength. (a) -1 order diffraction efficiency; (b) polarization sensitivity

Fig. 7. NP diffraction efficiency distribution of encapsulated grating at (a) different thicknesses of Al₂O₃ and SiO₂; (b) different groove depths and filling factors

Fig. 8. -1 order NP diffraction efficiency of encapsulated grating as a function of TiO₂ excess thickness

Fig. 9. Polarization sensitivity (PS) distribution of encapsulated grating at (a) different thicknesses of Al₂O₃ and SiO₂; (b) different groove depths and filling factors

Fig. 10. Polarization sensitivity of encapsulated grating as a function of TiO₂ excess thickness

Fig. 11. Fabrication process diagram of encapsulated grating

Fig. 12. Characterization results of grating structure. (a) Fused silica transmission grating; (b) encapsulated grating

Fig. 13. Fabrication model diagram of encapsulated grating

Fig. 14. Comparison between experimental and theoretical values of grating diffraction efficiency under TE and TM polarized incidence. (a) TE polarized incidence; (b) TM polarized incidence

Fig. 15. Comparison between experimental and theoretical values of encapsulated gratings. (a) NP diffraction efficiency;