The advancement of silicon photonics promises integrated optical switches to provide high-bandwidth, low-latency, and low-power communications in data centers. An optical switch’s loss limits its scale and affects the energy efficiency of the switch system. In this paper, we present cross-layer optical switch optimization (CLOSO), a cross-layer optimization (CLO) framework, based on not only photonic device models at the physical layer but also optical switch models at the fabric layer. With the proposed framework, optimal losses of optical switches can be evaluated efficiently, and the corresponding losses and design parameters of photonic devices can be obtained. Using CLOSO, we optimize four categories of integrated optical switches, Crossbar, PILOSS, DRAGON, and FODON, and compare them regarding their optimal worst-case loss with variation of the switch scale and data rate of signals. Furthermore, system-level evaluations of the optimized optical switches are performed, demonstrating a significant improvement of energy efficiency from the CLO. For instance, CLOSO helps to reduce the energy consumption of a 64-port DRAGON and FODON to as low as 6 pJ/bit and that of a 128-port DRAGON and FODON to as low as 10 pJ/bit. The investigation of 128-port switches also shows the necessity of adaptive power control on lasers for high-radix integrated optical switches. Through quantitative analyses and comparisons, CLOSO shows the capability of facilitating initial design exploration of optical switches and paves the way to fair evaluations and comparisons of switch systems in data centers.

中文翻译：

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数据中心集成光交换机的跨层优化框架

硅光子学的进步使集成光开关有望在数据中心提供高带宽、低延迟和低功耗的通信。光开关的损耗会限制其规模并影响开关系统的能效。在本文中，我们提出了跨层光开关优化 (CLOSO)，一种跨层优化 (CLO) 框架，不仅基于物理层的光子器件模型，还基于结构层的光开关模型。使用所提出的框架，可以有效地评估光开关的最佳损耗，并可以获得相应的光子器件损耗和设计参数。使用CLOSO，我们优化了四类集成光开关，Crossbar、PILOSS、DRAGON、FODON，并将它们的最佳最坏情况损耗与开关量程和信号数据速率的变化进行比较。此外，对优化的光开关进行了系统级评估，证明了 CLO 能效的显着提高。例如，CLOSO 有助于将 64 端口 DRAGON 和 FODON 的能耗降低到 6 pJ/bit，将 128 端口 DRAGON 和 FODON 的能耗降低到 10 pJ/bit。对 128 端口开关的研究还表明，对于高基数集成光开关的激光器进行自适应功率控制的必要性。通过定量分析和比较，CLOSO展示了促进光开关初始设计探索的能力，并为数据中心开关系统的公平评估和比较铺平了道路。