Fig. 1. Fabrication process. (a) LiNbO₃ substrate; (b) proton exchange; (c) photoresist spin-coating; (d) photolithography; (e) etching; (f) removal photoresist

Fig. 2. Effective area under different diffusion depths of waveguides when Δne is 0.08

Fig. 3. Effective area under different widths of waveguides when Δne is 0.08

Fig. 4. Effective area under different diffusion depths of waveguides when Δne is 0.1

Fig. 5. Effective area under different widths of waveguides when Δne is 0.1

Fig. 6. Flow of PSO algorithm

Fig. 7. Trend of effective mode field area under different iterations

Fig. 8. AWG structure diagram. (a) Schematic of AWG;(b) top view of the coupler

Fig. 9. Coupler light field diagrams. (a) Optical field profile of input coupler; (b) optical field profile of output coupler

Fig. 10. Transmission efficiency of each array waveguide

Fig. 11. Transmission spectra of AWG