High-Endurance, Low-Loss Sb₂Se₃ Optical Switches on Silicon Nitride Using Transparent Conductive Heaters

We report an electrically actuated, low-loss nonvolatile optical switch based on the phase-change material (PCM) Sb₂Se₃ integrated on a silicon nitride (Si₃N₄) platform. The device is fabricated using an 8-in. Wafer-scale process flow, demonstrating the feasibility of scalable manufacturing for photonic integrated circuits (PICs). By employing adaptive voltage and transparent indium tin oxide (ITO) microheaters, reversible switching between the amorphous and crystalline states is achieved with an endurance exceeding 140 million switching cycles, establishing a new benchmark for nonvolatile integrated photonic memory and reconfigurable architectures. Furthermore, multilevel operation beyond 6 bits can be repeatably demonstrated by pulse-count-dependent gradual crystallization, enabling precise control of the optical phase. These results highlight a scalable and energy-efficient platform for high-density programmable and nonvolatile photonic integrated systems.