Fig. 1. Conceptual 3D model of proposed LN waveguide mode converter. (a) 3D side view; (b) layer construction; (c) top view and key dimensions

Fig. 2. Flow chart of PSO algorithm

Fig. 3. Structure, mode field distributions, mode insertion loss, and crosstalk between modes of designed TE₀-to-TE₁ LN waveguide mode converter. (a) Top view of structure; (b) simulated mode field distribution; (c) mode insertion loss and mode crosstalk; cross-sectional field distributions perpendicular to propagation directions of (d) input and (e) output

Fig. 4. Structure, mode field distributions, mode insertion loss, and crosstalk between modes of designed TE₀-to-TE₂ LN waveguide mode converter. (a) Top view of structure; (b) simulated mode field distribution; (c) mode insertion loss and mode crosstalk; cross-sectional field distributions perpendicular to propagation directions of (d) input and (e) output

Fig. 5. Effect of process error of etching groove width d on mode insertion loss and crosstalk between modes in TE₀-TE₁

Fig. 6. Effect of process error of etching groove width d on mode insertion loss and crosstalk between modes in TE_0-TE₂

Fig. 7. Effect of process error of etching groove sidewall angle α on mode insertion loss and crosstalk between modes in TE₀-TE₁

Fig. 8. Effect of process error of etching groove sidewall angle α on mode insertion loss and crosstalk between modes in TE₀-TE₂