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

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

Phase-field simulation of magnetic double-hole nanoring and its application in random storage

As an ideal high-density storage unit, magnetic nanorings have become a research hotspot in recent years. We can both study the evolution of microscopic state of magnetization and acquire macroscopic magnetic properties by micromagnetic simulation, which has thus been widely used. However, traditional micromagnetism cannot simulate complex stress state. Due to the introduction of microelasticity theory, the phase field method for magnetic materials can be used to calculate the coupling effect of stress and magnetic field. However, the computing model usually needs to satisfy periodic boundary condition. In this paper, the phase field simulation combined with the finite element method is employed. By using user defined element, the evolution of magnetic domain structures of the double-hole nanorings has been studied. In different diameter of the holes and external magnetic field direction, we have found seven kinds of magnetic domain evolution mechanism. Among them, the twin-vortex evolution mechanism with high stability and low demagnetization interference characteristics of advantages, has good application prospect in magnetic random-access memory (MRAM) unit