Thermal Challenges and Performance Optimization of ITO Microheaters for Photonic Integrated Circuits

Phase-change material (PCM) based optical switches enable low-power, large-scale integrated photonic networks through precise, nonvolatile splitting ratio control. The key technology lies in the material system and structural design of microsecond-scale, high-temperature-resistant microheaters. Indium tin oxide (ITO) microheaters offer advantages of low fabrication complexity and compatibility with passive photonic platforms. However, their thermal stability issues during switching operations lead to poor cycling reliability in PCM-based phase shifters. Here, we overcome this challenge through geometric optimization of ITO microheaters, suppressing current crowding to achieve transient thermal stability at 1400 K during 5-μs pulsed operation─significantly exceeding the temperature requirements for PCM quenching. We characterize the switching speed by constructing a Mach–Zehnder interferometer (MZI) optical switch, demonstrating a fast response time of 2 μs while maintaining a low insertion loss of only 0.5 dB. These results establish ITO as a transformative platform for energy-efficient, reconfigurable photonic routers in AI-driven computing architectures.