中心教师徐绍夫的工作——Parallel optical coherent dot-product architecture for large-scale matrix multiplication with compatibility for diverse phase shifters（基于并行光学点积核的大规模矩阵计算架构）的相关成果近期被Optics Express期刊接收发表，该工作得到了国家重点研发计划（2019YFB2203700）、国家自然科学基金（T2225023, 62205203）的部分资助。现有相干光学矩阵计算架构需要由多级移相器串联构成，在执行大规模矩阵计算时串联移相器积累大量插入损耗，降低计算信噪比，限制了计算规模、吞吐量、信噪比与计算密度的同步提升。本文提出一种并行化光学点积核架构，创新利用双层交叉波导的拓扑结构设计，将大规模移相器进行全并联连接，移相器的插入损耗仅积累一次，可大幅降低由于移相器导致的插入损耗，破解了计算规模与插损之间的直接关联。此外，由于对移相器插损敏感度低，可以采用更多集成材料与工艺以实现低功耗、高密度的集成，仿真结果表明可使吞吐率提升约100倍，能量效率提升约10倍。本工作的提出为光计算技术的发展提供新方法，也为计算密集型应用提供潜在解决方案。
摘要:Photonics physically promises high-speed and low-consumption computing of matrix multiplication. Nevertheless, conventional approaches are challenging to achieve large throughput, high precision, low power consumption, and high density simultaneously in a single architecture, because the integration scale of conventional approaches is strongly limited by the insertion loss of cascaded optical phase shifters. Here, we present a parallel optical coherent dot-product (P-OCD) architecture, which deploys phase shifters in a fully parallel way. The insertion loss of phase shifters does not accumulate at large integration scale. The architecture decouples the integration scale and phase shifter insertion loss, making it possible to achieve superior throughput, precision, energy-efficiency, and compactness simultaneously in a single architecture. As the architecture is compatible with diverse integration technologies, high-performance computing can be realized with various off-the-shelf photonic phase shifters. Simulations show that compared with conventional architectures, the parallel architecture can achieve near 100× higher throughput and near 10× higher energy efficiency especially with lossy phase shifters. The parallel architecture is expected to perform its unique advantage in computing-intense applications including AI, communications, and autonomous driving.