Fig. 1. Anisotropic etching of (100) monocrystalline silicon

Fig. 2. Schematics of echelle grating. (a) Traditional echelle grating; (b) silicon echelle grating

Fig. 3. Diffraction efficiency varying with platform duty ratio f at different working orders. (a) 47; (b) 41; (c) 36

Fig. 4. Tolerance analysis of grating platform duty ratio

Fig. 5. Fabrication process of echelle gratings. (a) Substrate pre-processing; (b) oxide layer growing; (c) photoresist spinning; (d) ultraviolet exposure and development; (e) oxygen plasma etching; (f) ICP etching; (g) wet etching; (h) high-reflecting film coating

Fig. 6. Grating after mask collapse under optical microscope

Fig. 7. Schematic of over-etching after reaching the self-stopping surface

Fig. 8. SEM photos of silicon echelle grating with or without crystal alignment. (a) Without crystal alignment; (b) with crystal alignment

Fig. 9. SEM photos of 42 lp/mm silicon echelle grating. (a) Magnification of 300×; (b) magnification of 1000×

Fig. 10. Grating photos after coating. (a) Top view; (b) dispersion diagram

Fig. 11. Schematic of diffraction efficiency testing device of echelle grating

Fig. 12. Measurement results of diffraction efficiency at corresponding blazed wavelength of working orders

Fig. 13. Test results of grating sidewall surface roughness