Implementing fractional order Fourier transformation and confocal imaging with microwave computational metamaterials

¹ State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Engineering Science, College of Engineering, Peking University - Beijing 100871, China
² Materials Evaluation Center for Aeronautical and Aeroengine Applications, Beijing Institute of Aeronautical Materials, Beijing 100095, China

^(a) peiym@pku.edu.cn

Received: 10 December 2019
Accepted: 4 July 2020

Abstract

Computational metamaterials, artificially structured materials, have enabled the realization of mathematical operations, such as spatial integration, differentiation, and convolution when waves propagate through them. However, experimental verifications and relevant applications of microwave computational metamaterials have rarely been achieved so far. In this paper, we present the theoretical and experimental study on analog computing based on microwave computational metamaterials, to perform mathematical operations, such as fractional order Fourier transformation. To achieve such functionality, microwave metamaterials constructed with negative-refractive-index units are designed to implement the desired spatial operating function. We also explore the applications of the microwave metamaterial lens in the safety inspection of 3D printed objects and slice imaging by following the confocal imaging algorithm. We get good imagine results with high depth resolution at low frequencies. The technique allows us to demonstrate new approaches to real-time, multifunctional operating systems. We expect that microwave computational metamaterials will enable new capabilities in nondestructive testing (NDT) as well as signal acquisition and processing, improve microwave imaging, and drive new applications of microwaves.