Large-Scale High-Density Multimode Optical Switch Matrix

Optical switching technology is emerging as a solution to the limitations of traditional electronic switching. Combining optical switching with mode-division multiplexing effectively overcomes the limitations of expanding switching capacity solely by increasing the number of ports. This paper introduces a compact four-mode 2 × 2 optical switch and a four-mode reconfigurable non-blocking 4 × 4 optical switch matrix based on the Beneš architecture. The multimode 2 × 2 switch achieves an extinction ratio larger than 15 dB for all modes in the wavelength range of 1530–1590 nm. The multimode 4 × 4 switch matrix has an extinction ratio exceeding 9 dB for all modes and states in the C-band, with a compact size (1.46 × 0.23 mm²) and low power consumption (0–154 mW). It supports high-integrity 50 Gbaud PAM4 signal transmission with a bit error rate below the forward error correction limit. These devices pave the way for enhanced integration density and capacity in optical switching systems.