Meta-DFT Article is Published on Advanced Optical Material

I am very happy to announce that our work on analog computing based on metalens arrays has been published in Advanced Optical Materials.

The Promise and The Challenge

Photonic computing promises incredible speedups for tasks requiring a high degree of parallelism, such as image processing and neural networks. Computing with optical wave allows for parallel processing at a fundamental physical level. However, because this platform relies on analog computing, error control becomes an important challenge, especially when scaling up for larger computations.

Our Solution: Metalens array platform

In this work, we present a proof-of-concept experimental demonstration of performing a Discrete Fourier Transform (DFT) using a metalens array platform.

In classical optics, we learn that a conventional lens can perform a Fourier Transform simply by focusing light. In our approach, a metalens array generates multiple discrete focal points to perform a discrete Fourier transform.

But there is more to the story:

Phase Retrieval: We added an additional metalens, which we call a reference metalens, to probe the phase at the focal plane. This allows us to easily capture the full complex output field using interferometry.
Error Mitigation: Once we know the phase at the focal plane, we have complete information about the output. This is crucial for formulating a calibration procedure, allowing us to perform error mitigation to accommodate alignment or fabrication errors.

metadft-fig1 Graphical Abstract for Meta-DFT scheme

The Journey

This manuscript has been in preparation since the end of last year. It began as a modest extension of a previous study, but as we dug deeper, we realized we had the potential for a much more elegant story. We expanded the scope to treat the metasurface as a true platform for analog Matrix-Vector Multiplication (MVM), complete with a novel error mitigation strategy.

Personally, this is one of my proudest contributions. The effort was validated earlier this year when I had the privilege of presenting this project at the iSPN 2025 conference at the National University of Singapore. Receiving the Best Paper Award from the distinguished Prof. Nader Engheta was a highlight of my career so far!

stefan-ispn-award Me receiving Best Paper Award from Prof. Nader Engheta