Nonvolatile Continuously Tunable Integrated Optical Router

Abstract

Reconfigurable optical routers integrated into waveguides are vital for on‐chip all‐optical connectivity, promising revolutionary flexibility and efficiency for classical and quantum optical information processing. Conventional reconfiguration methods (thermo‐optic, free carrier dispersion, Pockels effect) often suffer from bulky sizes or high static power consumption, limiting scalability. We demonstrate, for the first time, a nonvolatile continuously tunable integrated optical router on a CMOS‐backend silicon‐on‐insulator (SOI) platform. This router employs Mach‐Zehnder optical switches with antimony sulfide (Sb₂S₃) phase shifters. Utilizing the Sb₂S₃ cell's nonvolatile phase change via a doped silicon microheater enables continuous forward switching and over 7 bits (128 levels) of reverse switching with zero static power. The nearly pure phase tuning capability of 0.3 dB/π achieves a high extinction ratio exceeding 18 dB. The phase shifter exhibits an insertion loss below 0.6 dB and endured over 1500 switching cycles using electrical pulses of varying voltage/duration for Joule heating. Additionally, the phase shifter supports MHz‐speed volatile switching via the thermo‐optic effect. This continuously tunable method provides superior precision over traditional non‐volatile multilevel techniques and effectively mitigates accumulated transmission errors in large‐scale Optical Network‐on‐Chip (ONoC) systems, removing a major obstacle to practical optical communication and computing implementation.