Fig. 1. (a) 3D structure view; (b) Cross-section view; (c) Schematic of waveguide layer structure

Fig. 2. Relationship between waveguide width and effective refractive index

Fig. 3. Electric field diagrams of three modes in 0.7 μm waveguides

Fig. 4. (a) Relationship between tapered coupler length and coupling efficiency in TE₀₀ mode; (b) Relationship between tapered coupler length and coupling efficiency in TE₀₁ mode; (c) Relationship between length of tapered structure and coupling efficiency before and after maximum efficiency; (d) Relationship between the length of the conical structure used to shrink the spot shape and the coupling efficiency

Fig. 5. Coupling efficiency of tapered structures at 1.26-1.35 μm wavelength

Fig. 6. Electric field diagram of evanescent coupling structure

Fig. 7. (a) Relationship between etch depth and reflectivity; (b) Reflectivity spectra of different duty cycles; (c) Relationship between grating length and reflectivity

Fig. 8. Reflectivity of Bragg grating lengths at 110 μm and 240 μm