Ultra-compact grating-coupled nanophotonic resistive switch.

Minimizing the footprint of nonvolatile photonic memories is essential for high-density programmable photonic integrated circuits. Here, we present an ultra-compact grating-coupled nanophotonic resistive switch based on a hybrid Ag/SiO2/ITO platform on an SOI substrate. The engineered device simultaneously integrates optical coupling, hybrid mode confinement, and resistive switching within a single engineered grating structure, resulting in a total device length of only ~24 µm, including the input coupling, active switching, and output coupling regions. Strong optical confinement within the ultrathin SiO2 layer enables efficient electro-optic modulation with an extinction ratio of 19.4 dB. The device exhibits stable bipolar switching with SET/RESET voltages of +3.2 V/-3 V, endurance over 200 cycles, and retention exceeding 104 s. Transient measurements reveal successful switching under 5 µs programming pulses with an effective switching time of ~100 ns. The demonstrated ultra-compact footprint and nonvolatile optical functionality make the proposed device promising for high-density photonic memories, programmable photonic integrated circuits, nonvolatile photonic computing, and memory systems.