Nonvolatile Continuously Tunable Integrated Optical Router

Abstract

<p>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.</p>