Fig. 1. (a) Schematic diagram of the proposed mode splitter; (b) boundary shape of the mode splitter.

Fig. 2. Design flow of the mode splitter. (a) Initial structure of the device; (b) simulation stage of device design; (c) optimization of the device shape using Python; (d) optimized structure of the device.

Fig. 3. Boundary shape evolution and FOM evolution for (a) mode splitter and (b) mode (De)MUXer; simulated electric field distribution for (c) mode splitter and (d) mode (De)MUXer.

Fig. 4. Simulated transmission spectra for (a) mode splitter as TE₀ input, (b) mode splitter as TE₁ input, (c) mode (De)MUXer as TE₀ input, and (d) mode (De)MUXer as TE₁ input.

Fig. 5. Simulated transmission spectra of the mode splitter when (a) ΔW = −20 nm and TE₀ input; (b) ΔW = −20 nm and TE₁ input; (c) ΔW = +20 nm and TE₀ input; and (d) ΔW = +20 nm and TE₁ input. Simulated transmission spectra of the mode (De)MUXer when (e) ΔW = −20 nm and TE₀ input; (f) ΔW = −20 nm and TE₁ input; (g) ΔW = +20 nm and TE₀ input; and (h) ΔW = +20 nm and TE₁ input.

Fig. 6. Microscopic view of the fabricated (a) mode splitter, (b) ADC reference, and (c) mode (De)MUXer. Zoom-in view of the fabricated (d) mode splitter and (e) mode (De)MUXer.

Fig. 7. Normalized transmission spectra of (a) mode splitter as TE₀ input, (b) mode splitter as TE₁ input, (c) mode (De)MUXer as TE₀ input, (d) mode (De)MUXer as TE₁ input.