Fig. 1. Summary of the inverse-designed power splitters. A: The power splitter with four channels ^[62]; B: The power splitter with a split ratio of 1:2:1^[63]; C: The power splitter for the TE₀, TE₁, and TE₂ modes ^[70]; D: The power splitter with 700 nm working bandwidth ^[71]; E: The tunable power splitter ^[72]

Fig. 2. Summary of the forward design and inverse design methods

Fig. 3. Structures and results of the single-device power splitters with multiple channels. (a) and (b) The 1 × 2 power splitter^{[75, 79]}; (c) The 1 × 3 power splitter ^[86]; (d) The 1 × 4 power splitter ^[62]

Fig. 4. Structures and results of the assembled power splitters with multiple channels. (a) The 1 × 4 power splitter assembled by three 1 × 2 power splitters with different output directions ^[60]; (b) The 1 × 6 power splitter assembled by one 1 × 2 power splitter and two 1 × 3 power splitters ^[86]

Fig. 5. Structures and results of the power splitters with arbitrary split ratios. (a) The 1 × 3 power splitter with a split ratio of 1:2:1^[87]; (b) The 1 × 2 power splitters with the split ratios of 1:1, 1:2, and 1:3 ^[63]; (c) The 1 × 2 power splitter with the split ratios of 9:1, 8:2, 7:3, and 6:4 ^[88]

Fig. 6. Forward and inverse neural network modeling ^[89]

Fig. 7. Structures and results of the single-device power splitters with multiple modes. (a) The two-TE-mode power splitter ^[90]; (b) The three-TE-mode power splitter ^[70]; (c) The four-mode and dual-polarization power splitter ^[93]

Fig. 8. Structures and results of the assembled power splitter with multiple modes ^[94]. (a) The SEM images; (b) The simulated light field distributions; (c) The measured transmission spectra

Fig. 9. Structures and results of 1×4 power splitter working at 2 μm spectral range ^[95]

Fig. 10. Structures and results of the broadband power splitters. (a) The 1×4 power splitter with 300 nm working bandwidth ^[96]; (b) The 1×2 power splitter with 445 nm working bandwidth ^[97]; (c) The 1×2 power splitter with 550 nm working bandwidth ^[98]; (d) The 1×2 power splitter with 700 nm working bandwidth ^[71]

Fig. 11. Structures and results of the combined-functional power splitters. (a) The power splitter with different output directions ^[86]; (b) The power splitter with the arbitrary input waveguides ^[100]; (c) The power splitter with the mode conversion^[101]; (d) The power splitter with the mode conversion and wavelength demultiplexing ^[102]

Fig. 12. Structures and results of the tunable power splitters. (a) The GST-based power splitter with the reconfigured power ratios ^[72]; (b) The GSST-based power splitter with the straight passing and power splitting ^[103]; (c) The Sb₂Se₃-based power splitter with the reconfigured power ratios ^[104]