Near-zero power tuning! Chinese team breaks through the bottleneck of optical interconnect chips and creates non-volatile intelligent programmable micro-ring array optical transceiver chips

As AI model parameters surge beyond trillions, the computational clusters required for training grow exponentially. Traditional XPU interconnects now face a critical bandwidth bottleneck that throttles computing power – making interconnect enhancement an urgent priority. Optical interconnect technology emerges as a transformative solution, leveraging its ultra-large bandwidth, minimal loss, and low crosstalk to enable higher-speed, lower-power connections. Within this domain, silicon photonics has gained significant traction due to its CMOS compatibility and high integration potential. Micro-ring resonators (MRRs) stand out as particularly promising components, offering substantially smaller footprints and lower power consumption than traditional Mach-Zehnder interferometer (MZI) modulators, making them ideal for future high-density optical I/O. Yet silicon MRRs face commercialization hurdles from manufacturing variations and temperature sensitivity. Addressing these challenges, a Shanghai Jiao Tong University (SJTU) research team achieved a breakthrough by heterogeneously integrating thin films of low-loss phase-change material Sb2Se3 onto silicon MRR PN junctions. Using a silicon photonics back-end-compatible process, they created non-volatile, "smart-programmable" micro-ring transceivers. Applying forward-biased electrical pulses induces reversible phase transitions (crystallineamorphous) in Sb2Se3, enabling precise resonance wavelength tuning across the entire free spectral range. Crucially, experiments confirmed that phase-change material integration minimally impacts modulation and detection performance. The team then designed and fabricated a transceiver chip using four cascaded Sb2Se3-Si MRRs. Leveraging phase transitions for uniform resonance distribution, they demonstrated 100 Gbps On-Off Keying (OOK) modulation and detection per micro-ring, achieving a total data rate of 400 Gbps. Furthermore, they innovated a scalable feedback scheme using one MRR as an optical power monitor to detect temperature fluctuations. This enables compensation via global temperature control, simultaneously stabilizing multiple adjacent MRRs while significantly reducing the hardware overhead for thermal management.

This research successfully merges low-loss Sb2Se3 with silicon MRRs, enabling efficient wavelength tuning and high-speed data transmission while solving critical system-application bottlenecks. It provides a robust pathway for developing next-generation high-density, low-power optical interconnect chips. Looking ahead, further optimization promises to accelerate MRR technology from lab to industry, catalyzing transformation in data center interconnects and high-speed communication networks. Simultaneously, this work exemplifies powerful multidisciplinary convergence, inspiring researchers to pioneer novel photonics-integration approaches that could spawn disruptive technologies and inject powerful momentum into the sustainable evolution of optical communications.