Mode-insensitive optical switch based on inverse-designed adiabatic directional couplers and asymmetric Y-junctions

Mode-division multiplexing (MDM) technique reactivates optical interconnect as it offers a new dimension to enhance the transmission capacity of a single wavelength carrier. As a fundamental building block for MDM communication systems, the multimode optical switch plays an important role in dynamic light routing during optical interconnection. However, due to the mismatched effective refractive indices and modal field profiles, conventional multimode optical switches exhibit modulation efficiency imbalance, narrow bandwidth, and high power-consumption. Here, we propose and experimentally demonstrate an energy-efficient and mode-insensitive optical switch by employing an efficient inverse design method. The fabricated device exhibits extinction ratios of larger than 13.12 and 13.06 dB, and the crosstalks of less than -12.92 and -12.78 dB for E₁₁ and E₂₁ modes, respectively, with the switching power of less than 10.75 mW across 1510 to 1570 nm. The proposed switch enables energy-efficient and mode-insensitive dynamic routing for MDM systems, supporting scalable optical network architectures.