Nonlinear Analog Processing with Anisotropic Nonlinear Films

TL;DR

This paper introduces nonlinear optical operations using anisotropic nonlinear films in metasurfaces, enabling advanced analog optical processing beyond linear Fourier optics, demonstrated through broadband edge detection.

Contribution

It presents the first implementation of nonlinear optical functionalities in metasurface-based analog processing, expanding capabilities beyond linear regimes.

Findings

Demonstrated nonlinear optical operations with anisotropic nonlinear films

Achieved broadband, polarization-selective edge detection

Paved the way for new nonlinear analog optical processing applications

Abstract

Digital signal processing is the cornerstone of several modern-day technologies, yet in multiple applications it faces critical bottlenecks related to memory and speed constraints. Thanks to recent advances in metasurface design and fabrication, light-based analog computing has emerged as a viable option to partially replace or augment digital approaches. Several light-based analog computing functionalities have been demonstrated using patterned flat optical elements, with great opportunities for integration in compact nanophotonic systems. So far, however, the available operations have been restricted to the linear regime, limiting the impact of this technology to a compactification of Fourier optics systems. In this paper, we introduce nonlinear operations to the field of metasurface-based analog optical processing, demonstrating that nonlinear optical phenomena, combined with nonlocality in flat optics, can be leveraged to synthesize kernels beyond linear Fourier optics, paving the way to a broad range of new opportunities. As a practical demonstration, we report the experimental synthesis of a class of nonlinear operations that can be used to realize broadband, polarization-selective analog-domain edge detection.