Correspondents | Shihuan Ran, Liangjun Lu, Yu Li
Paper Title | Field programmable silicon microring WDM transceiver leveraging monolithically integrated phase-change materials
Authors | Xing Yang1, Shihuan Ran1, Ziquan Li1, Liangjun Lu1,2, Yu Li1,2, Ngon Phu Wai3, MingHua Zhang3, GuoQiang Lo3, Jianping Chen1,2, Linjie Zhou1,2
Affiliation | Shanghai Jiao Tong University, Singapore Advanced Microelectronics Pte Ltd
Research Background
As artificial intelligence (AI) applications demand higher precision and broader capabilities, the parameter scale of large language models has exceeded trillions, requiring increasingly larger training clusters. The limited interconnect bandwidth between traditional XPUs is becoming a computational bottleneck, making it imperative to enhance interconnect bandwidth. Optical interconnect technology, with its advantages of ultra-large bandwidth, extremely low loss, and crosstalk, enables higher bandwidth and lower power consumption interconnects. Silicon photonics, compatible with CMOS processes and capable of high integration, has become a research hotspot in the optical interconnect field. Compared to traditional Mach-Zehnder Interferometer (MZI) modulators, microring resonators (MRRs), with their small size and low power consumption, can meet the high-density, low-power interconnect requirements of optical I/O. However, silicon-based MRRs are susceptible to manufacturing process variations and environmental temperature fluctuations, posing significant challenges to their commercial application.
Introduction
The Photonics National Key Laboratory team led by Professor Linjie Zhou has published a breakthrough achievement in PhotoniX: by heterogeneously integrating low-loss phase-change material Sb₂Se₃ with silicon-based microring resonators, they have achieved the world's first near-zero-power "intelligently programmable" optical transceiver chip. Applying electrical pulses to the PN junction in the microring triggers a phase change, achieving non-volatile wavelength tuning with a precision of 10 pm and exceeding one free spectral range (FSR). This meets the wavelength calibration needs of microring arrays while effectively eliminating static power consumption for state maintenance. The research team also proposed an innovative feedback mechanism to suppress thermal drift, successfully demonstrating high-speed transmission and reception with a 4-channel programmable microring array, achieving a total data rate of 400 Gbps.
Features
This research exemplifies the integration of photonics and materials science. Breaking disciplinary barriers, the team introduced the low-loss phase-change material Sb₂Se₃ from materials science into silicon photonics, applying it to high-speed silicon-based optical transceiver chips. Through the heterogeneous integration of phase-change materials with silicon photonic devices, precise post-trimming of the MRR resonant wavelength was achieved. This interdisciplinary innovative thinking not only solves challenges in optical device system applications but also expands the application boundaries of phase-change materials in photonics, providing a novel approach for promoting technological innovation through multidisciplinary integration.
Main Research Content
The research team conducted an in-depth study on optimizing the performance of silicon microring resonators. They heterogeneously integrated a thin film of low-loss phase-change material Sb₂Se₃ onto the PN junction of silicon-based MRRs using a post-back-end-of-line (post-BEOL) compatible process to realize a non-volatile "intelligently programmable" microring transceiver. By applying forward-biased electrical pulses, Sb₂Se₃ can be switched between crystalline and amorphous states, enabling flexible tuning of the resonant wavelength across the entire FSR. Experiments confirmed that the integration of the phase-change material has almost no impact on the modulation and detection performance, ensuring the feasibility of the technology. Subsequently, a transceiver chip based on four cascaded Sb₂Se₃-Si heterogeneously integrated MRRs was designed and fabricated. Using phase change, uniform distribution of resonant wavelengths was achieved, and successful demonstration of on-off keying (OOK) modulation and detection was performed, with a single microring rate of 100 Gbps and a total rate of 400 Gbps. Furthermore, the team proposed an innovative feedback scheme utilizing one of the MRRs as an optical power monitor to feed back temperature fluctuation information, compensating for the impact of ambient temperature changes on device performance through global temperature control. This scheme shows promise for simultaneously stabilizing the operating states of multiple adjacent MRRs, offers scalability, and reduces the hardware requirements for temperature feedback control.
Technological Breakthroughs and Innovations
This research achieved significant technological breakthroughs and innovations in several aspects:
Material Integration: Developed a post-BEOL compatible heterogeneous integration technology for phase-change materials, directly integrating low-loss Sb₂Se₃ into silicon-based MRR transceivers. Leveraging the non-volatile nature of phase-change materials, it breaks the limitation of traditional MRR resonant wavelength calibration relying on additional static power consumption, simplifies device structure, reduces chip area, and creates conditions for large-scale integration.
Wavelength Tuning Technology: Innovatively utilized forward biasing of the PN junction to induce phase change, achieving bidirectional resonant wavelength adjustment with a tuning range exceeding one FSR. The tuning process requires only millisecond-level electrical pulses, making it faster and more flexible compared to traditional methods and enabling field programmability.
System Performance Optimization: Cascaded integration of Sb₂Se₃ transceivers achieved high-speed data transmission at 4×100 Gbps. Concurrently, the proposed feedback scheme effectively addresses temperature fluctuation issues, significantly enhancing system stability and reliability.
This comprehensive innovation, spanning from materials to devices and systems, opens a new path for the commercial application of silicon-based MRRs in the field of optical interconnects.
Fig. 1 Structure of low-loss phase-change material Sb₂Se₃ integrated onto the PN junction of a silicon microring resonator, clearly showing the combination of material and device.
Commentary
This research successfully demonstrates the heterogeneous integration of low-loss phase-change material Sb₂Se₃ with silicon microring resonators, achieving efficient wavelength tuning and high-speed data transmission. It effectively addresses key challenges faced by silicon-based microring transceiver chips in system applications, providing a reliable solution for the development of next-generation high-density, low-power optical interconnect chips. Looking ahead, with further technological optimization and refinement, this innovative achievement is expected to accelerate the transition of microring resonator devices from the laboratory to industrial application, driving transformation in fields such as data center optical interconnects and high-speed communication networks. Simultaneously, this research also serves as a model for multidisciplinary交叉research, inspiring more researchers to explore innovative paths integrating optics with other disciplines, potentially催生more disruptive technologies and injecting new momentum into the sustainable development of the optical communication industry.
Introduction of Main Authors
Xing Yang, Ph.D. candidate (2019 intake) at Shanghai Jiao Tong University Photonics National Key Laboratory, research direction: silicon-phase-change material hybrid integrated photonic devices.
Shihuan Ran, Ph.D. candidate (2020 intake) at Shanghai Jiao Tong University Photonics National Key Laboratory, research direction: silicon-based high-speed electro-optic modulators.
Article Source
Published in: PhotoniX
Article link: https://photonix.springeropen.com/articles/10.1186/s43074-025-00174-7
Citation: PhotoniX 6, 17 (2025). https://doi.org/10.1186/s43074-025-00174-7
