Fig. 1. Simulation of waveguide single-mode condition

Fig. 2. Schematic diagram of bragg grating

Fig. 3. Relationship between grating coupling coefficient and grating structure

Fig. 4. FWHM and reflectivity of gratings with different coupling coefficients

Fig. 5. Process flow diagram of waveguide grating chip

Fig. 6. Schematic diagram and SEM of waveguide section

Fig. 7. Microscopic photos and physical images of bragg gratings at different dutys

Fig. 8. Schematic diagram of test platform

Fig. 9. Reflection spectrum of Bragg grating at different dutys

Fig. 10. Reflection spectra of Bragg gratings at different etching depths

Fig. 11. Center wavelength of Bragg grating at different dutys

Fig. 12. FWHM of Bragg grating at different etching depths