High-efficiency lithium niobate optical mode switch using a mode-loop Mach-Zehnder interferometer

Mode-division multiplexing is a common technology in photonic integrated circuits, which can combine various optical mode signals into one single channel such as a multimode waveguide to improve the communication system's capacity. Optical mode switch plays a critical role in mode-division multiplexing, which can switch the optical signal into different mode channels. Here, we propose and experimentally demonstrate a high-efficiency optical mode switch with a half-wave voltage length product (V_πL) of about 1.83 V·cm, an extinction ratio of 22.9 dB, and a switching time below 48.3 ps, using mode-loop Mach-Zehnder interferometer structure in the lithium niobate on insulator platform. This optical mode switch has a potential application in supporting high-speed data transmission for on-chip mode-division-multiplexing systems.