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

• DOI: 10.1038/s41566-024-01394-2
• Publication Date: 2024-02-16T11:05:22Z
• Authors: Vahid Nikkhah; Ali Pirmoradi; Farshid Ashtiani; Brian Edwards; Firooz Aflatouni; Nader Engheta
• Keywords: Matrix (chemical analysis)

29 pages (including the main text and the supplementary materials), 10 figures (4 for the main text and 6 for supplementary materials)<br/>Inverse-designed Silicon photonic metastructures offer an efficient platform to perform analog 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 utilizes 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 2D inverse-design method based on the effective index approximation with a low-index contrast constraint. This results in compact amorphous lens systems which are generally feed-forward and low-resonance. We designed and experimentally demonstrated a vector-matrix product for a 2 x 2 and a 3 x 3 matrix. We also designed a 10 x 10 matrix using the proposed 2D computational method. These examples demonstrate that these techniques have the potential to enable larger-scale wave-based analog computing platforms.<br/>