Silicon photonic MEMS 2 × 2 elementary switch based on horizontal adiabatic directional couplers

High-speed data processing requires large-scale photonic integrated circuits, in which photonic switches serve as essential components for reconfiguration. Micro-electromechanical-system (MEMS)-based photonic switches, particularly those utilizing adiabatic directional couplers (ADCs), offer advantages such as broad bandwidth, exceptional fabrication tolerance, and digital operation. However, previous ADC-based switches are limited to 1 × 2 configurations, restricting their compatibility with diverse array topologies. Here, we propose a novel silicon photonic MEMS 2 × 2 switch based on horizontal ADCs (HADCs) which is compatible with all mainstream array topologies. In simulation, the switch features low insertion loss of 6-19 mdB/7-32 mdB and low crosstalk of -44.1 - -37.4 dB/-32 - -22.6 dB in broad bandwidth of 1500-1600 nm in the OFF/ON state, respectively. Experimental results demonstrate insertion loss of 0.15-0.7 dB/1.1-1.6 dB, crosstalk of -48.6 - -40.1 dB/-9.2 - -8.4 dB in the OFF/ON state, respectively. The measured switch performance in the ON state can be further improved by using more comprehensive coordinated photonic/mechanical design or low-strain SOI wafers to suppress the waveguide buckling in our future work. Additionally, fast ON/OFF switching speed of 2.6/1.8 μs and reliable durability of >10⁹ switching cycles have been demonstrated experimentally. This 2 × 2 switch design addresses critical limitations of previous architectures and is a promising approach for versatile applications including microwave photonics, photonic interconnects, LiDAR, and spectrometers.