Broadband and Low-Random-Phase-Errors 2 × 2 Optical Switch on Thin-Film Lithium Niobate

We propose and demonstrate a broadband and low-random-phase-errors 2 × 2 optical switch on thin-film lithium niobate platform. The proposed switch is based on a typical Mach-Zehnder interferometer constructed with two 2 × 2 3-dB multimode interferometer couplers, two few-mode waveguide (FMW) arms, and corresponding input and output waveguides. The use of FMWs can help to reduce the random phase errors and improve the fabrication tolerances. Over a wide optical bandwidth from 1530 nm to 1605 nm, our typical fabricated switch can work on the desired initial operating state and achieve an extinction ratio mostly larger than ∼16 dB. The switching voltage is ∼7.3 V. The rise and fall times are 134.4 ns and 8.8 ns, respectively. This work can facilitate the development of optical switches on the lithium-niobate-insulator (LNOI) platform.