近日，美国宾夕法尼亚大学的Nader Engheta及其研究团队取得一项新进展。经过不懈努力，他们提出硅光子平台上针对向量矩阵乘法的反求设计方法。相关研究成果已于2024年2月16日在国际知名学术期刊《自然—光子学》上发表。

本文提出了一种基于有效折射率近似和低折射率对比度约束的二维反求设计方法。通过这种方法，成功设计出紧凑的非晶透镜系统，该系统具有前馈和低共振特性。研究人员不仅设计并实验验证了2×2和3×3矩阵的向量矩阵乘积，还创新地设计了一个10×10矩阵，并采用了所提出的二维计算方法。这些案例充分展示了这些技术在构建更大规模基于波的模拟计算平台上的巨大潜力。

据悉，硅光子元结构通过反求设计为电磁波模拟计算提供了高效平台。然而，受限于计算复杂性，将这些元结构扩展以处理庞大数据通道颇具挑战。此外，传统的反求设计流程通常在有限计算域内运行，往往依赖共振特性以达成目标，这导致了结构带宽狭窄且对制造误差敏感。

附：英文原文

Title: Inverse-designed low-index-contrast structures on a silicon photonics platform for vector–matrix multiplication

Author: Nikkhah, Vahid, Pirmoradi, Ali, Ashtiani, Farshid, Edwards, Brian, Aflatouni, Firooz, Engheta, Nader

Issue&Volume: 2024-02-16

Abstract: Inverse-designed silicon photonic metastructures offer an efficient platform to perform analogue computations with electromagnetic waves. However, due to computational difficulties, scaling up these metastructures to handle a large number of data channels is not trivial. Furthermore, a typical inverse-design procedure is limited to a small computational domain and therefore tends to employ resonant features to achieve its objectives. This results in structures that are narrow-bandwidth and highly sensitive to fabrication errors. Here we employ a two-dimensional (2D) inverse-design method based on the effective index approximation with a low-index contrast constraint. This results in compact amorphous lens systems that are generally feed-forward and low-resonance. We designed and experimentally demonstrated a vector–matrix product for a 2×2 matrix and a 3×3 matrix. We also designed a 10×10 matrix using the proposed 2D computational method. These examples demonstrate that these techniques have the potential to enable larger-scale wave-based analogue computing platforms.

DOI: 10.1038/s41566-024-01394-2

Source: https://www.nature.com/articles/s41566-024-01394-2