RESEARCH ARTICLE

Simulation and experimental investigation of liquid-cooling thermal management for high-bandwidth co-packaged optics  

Senhan Wu, Song Wen, Huimin He, Jianyu Feng, Chuan Chen, Haiyun Xue

2025, 18(2): 11.https://doi.org/10.1007/s12200-025-00156-4

Abstract: This study explores the application of cold plate liquid cooling technology in co-packaged optics (CPO). By integrating optical modules and the switch chip on the same substrate, CPO shortens the electrical interconnection distance, effectively solving the problems of high power consumption and poor signal integrity of traditional pluggable optical modules under high bandwidth. However, the surge in power density and the thermal crosstalk resulting from high integration density make thermal management one of the key challenges that constrain the reliability of high-capacity co-packaged optics. For the unique architecture of CPO, this study analyzes its heat dissipation needs in detail, and a thermal management scheme is designed. The thermal management scheme is simulated and optimized based on the Navier−Stokes equation. The simulation results show that, in a 51.2 Tbit/s CPO system, the junction temperature of the switch chip is 97.3 °C, the maximum junction temperature of the optical modules is 31.3 °C, and the temperature difference between the optical modules is 2.4 °C to 1.2 °C. To verify the simulation results, a thermal test experimental platform is built, and the experimental results show that the temperature simulation difference is within 4% and the pressure change trend is consistent with the simulation. Combining the experimental data and simulation results, the designed heat sink can satisfy the heat dissipation demands of the 51.2 Tbit/s bandwidth CPO system. This conclusion demonstrates the potential of liquid-cooling technology in CPO, providing support for research on liquid-cooling technology in the CPO. The design provides a theoretical and practical basis for the high performance and reliability of optoelectronic integration technology in wavelength division multiplexing (WDM) systems and micro-ring device applications, contributing to the application of next-generation optical communication networks.

研究背景：随着人工智能和机器学习技术的快速发展，数据中心面临着用户数量激增和数据交换需求巨大的挑战。传统的可插拔光模块技术因高功耗和信号完整性差等问题，已无法满足数据中心的需求。因此，共封装光学（Co-packaged Optics, CPO）技术应运而生。CPO通过将光模块和交换芯片集成在同一基板上，缩短了电互连距离，有效降低了功耗。然而，高集成密度导致的功率密度增加和热串扰问题，使得热管理成为制约高容量CPO可靠性的关键挑战。

主要内容：本研究探讨了液冷技术在CPO中的应用，针对CPO的独特架构，详细分析了其散热需求，并设计了一种热管理方案。该方案基于Navier-Stokes方程进行模拟和优化，以满足51.2 Tbit/s CPO系统的散热需求。

创新点：研究提出了一种双界面液冷散热结构，通过优化微通道的几何参数，显著降低了交换芯片的结温，并提高了光模块的温度均匀性。此外，通过实验验证了模拟结果的可靠性，证明了所设计的散热器能够满足51.2 Tbit/s带宽CPO系统的散热需求。

方法：

• 散热需求分析：CPO系统包含一个交换芯片和八个光模块，集成在同一基板上。随着带宽的增加，交换芯片的功耗显著增加，导致热通量高达1.79 W/mm²。因此，需要高效的散热方案来确保芯片的正常运行。

• 热管理方案设计：为了满足CPO系统的散热需求，设计了一种液冷散热结构。该结构包括两个独立的散热器，一个用于交换芯片，另一个用于光模块，以避免热串扰。

• 模拟优化和实验验证：使用Navier-Stokes方程模拟微通道中的流动和传热问题，优化散热结构。构建了热测试实验平台，实验结果表明，模拟与实验的温度差异在4%以内，压力变化趋势与模拟一致，证明了所设计散热器的有效性。

结果：

• 模拟结果：在51.2 Tbit/s CPO系统中，优化后的散热结构能够将交换芯片的结温降低到97.3°C，光模块的最高结温降低到31.3°C，温度差从2.4°C降低到1.2°C。

• 实验结果：实验验证了模拟结果的可靠性，证明了所设计的散热器能够满足51.2 Tbit/s CPO系统的散热需求。在1 L/min的流速下，交换芯片的最大结温为98.3°C，光模块的最大结温为35.1°C，最大温度差为1.5°C。

结论：本研究通过模拟和实验验证了液冷技术在CPO中的应用潜力，为下一代光通信网络中的光电集成技术提供了理论和实践基础。所设计的散热结构能够有效管理高容量CPO系统的热量，确保系统的高性能和可靠性。