Fig. 1. Schematic diagram of grating

Fig. 2. Diagram of grating structures

Fig. 3. Reflection spectra at different grating positions

Fig. 4. Transverse mode distribution in two structures

Fig. 5. Angle of side wall of grating and the relationship between dip angle, wavelength and reflectivity of grating

Fig. 6. Influence of grating angle on cavity loss

Fig. 7. Grating coupling coefficient varies with duty ratio and etching depth

Fig. 8. Relationship between etching depth of grating and coupling coefficient

Fig. 9. Relationship between etching depth, wavelength and reflectivity of the period

Fig. 10. Influence of etching depth of grating on loss