[1] [1] Puttnam BJ, et al. Space-division multiplexing for optical fiber communications. Optica. 2021;8(9):1186–203.

[2] [2] Ryf R, et al. Mode-division multiplexing over 96 km of few-mode fiber using coherent 6×6 MIMO processing. J Light Technol. 2012;30(4).

[3] [3] Chen M, et al. Iterative photonic processor for fast complex-valued matrix inversion. Photon Res. 2022;10(11):2488–501.

[4] [4] Chen M, et al. I/O-efficient iterative matrix inversion with photonic integrated circuits. Nat Commun. 2024;15(1):5926.

[5] [5] Wu B, et al. Programmable integrated photonic coherent matrix: Principle, configuring, and applications. Appl Phys Rev. 2024;11(1):011309.

[6] [6] Annoni A, et al. Unscrambling light—automatically undoing strong mixing between modes. Light Sci Appl. 2017;6(12):e17110.

[7] [7] Zhou H, et al. All-in-one silicon photonic polarization processor. Nanophotonics. 2019;8(12):2257–67.

[8] [8] Zhang W, et al. On-chip photonic spatial-temporal descrambler. Chip. 2023;2(2):100043.

[9] [9] Wu B, et al. Chip-to-chip optical multimode communication with universal mode processors. PhotoniX. 2023;4(1):37.

[10] [10] SeyedinNavadeh S, et al. Determining the optimal communication channels of arbitrary optical systems using integrated photonic processors. Nat Photon. 2024;18(2):149–55.

[11] [11] Lu K, et al. Empowering high-dimensional optical fiber communications with integrated photonic processors. Nat Commun. 2024;15(1):3515.

[12] [12] Cheng L, et al. Grating couplers on silicon photonics: design principles, emerging trends and practical issues. Micromachines. 2020;11(7).

[13] [13] Michaels A, et al. Inverse design of near unity efficiency perfectly vertical grating couplers. Opt Express. 2018;26(4):4766–79.

[14] [14] Wu Y, et al. Mode-selective coupling between few-mode fibers and buried channel waveguides. Opt Express. 2016;24(26):30108–23.