Parallel integro-differential equation solving via multi-channel reciprocal bianisotropic metasurface augmented by normal susceptibilities

Abstract

Analog optical signal processing has dramatically transcended the speed and energy limitations accompanied with its digital microelectronic counterparts. Motivated by recent metasurface's evolution, the angular scattering diversity of a reciprocal passive bianisotropic metasurface with normal polarization is utilized in this paper to design a multi-channel meta-computing surface, performing multiple advanced mathematical operations on input fields coming from different directions, simultaneously. Here, the employed ultra-thin bianisotropic metasurface computer is theoretically characterized based on generalized sheet transition conditions and susceptibility tensors. The operators of choice are deliberately dedicated to asymmetric integro-differential equations and image processing functions, like edge detection and blurring. To clarify the concept, we present several illustrative simulations whereby diverse wave-based mathematical functionalities have been simultaneously implemented without any additional Fourier lenses. The performance of the designed metasurface overcomes the nettlesome restrictions imposed by the previous analog computing proposals such as bulky profiles, asserting only single mathematical operation, and most importantly, supporting only the even-symmetric operations for normal incidences. Besides, the realization possibility of the proposed metasurface computer is conceptually investigated via picturing the angular scattering behavior of several candidate meta-atoms. This work opens a new route for designing ultra-thin devices executing parallel and accelerated optical signal/image processing.

Analogue Optical Spatiotemporal Differentiator

“…In recent years, many researchers have developed kaleidoscopic analogue optical spatial computing devices based on the transfer function method, including differentiators, [10][11][12][13][14][15][16][17][18][19][20][21] integrators, [13,22,23] equation-solvers. [24,25] All-dielectric optical materials have been extensively utilized to build high-efficiency optical analogue spatial computing devices. [13,14,[19][20][21][22][23] But it is still empty for a device to have the spatiotemporal operation which will possess more functionalities.…”

Meta-optics for spatial optical analog computing

“…Several other proposals and demonstrations using spin Hall effect (SHE) of light [65], prism coupling configuration [66], reflective hybrid plasmonic-dielectric metasurfaces [48], periodic plasmonic metasurfaces covered by graphene [67], multiinput-multioutput computational metasurfaces [68], ultrathin bianisotropic metasurfaces [69], polarization-insensitive structured surfaces with tailored nonlocality [70], and engineering the spatial dispersion of the electric dipole resonance in dielectric metasurfaces [71] to perform mathematical operators based on GF approach have been reported in the literature.…”

Flexible Manipulation of Emitting Beams Using Single‐Aperture Circularly Polarized Digital Metasurface Antennas: Multi‐Beam Radiation toward Vortex‐Beam Generation

“…Recent years have witnessed a clear tendency toward achieving multiple contour beams using fully planar metasurface‐based devices with a lighter weight and lower cost compared to the solid reflectors [ 6 ] and bulky metamaterials. [ 7 ] Metasurfaces, engineered arrays of artificially patterned microelements on a flat surface, have recently emerged as a flourishing concept which attracts tremendous interest because of providing peculiar routes to manipulate the phase, [ 8–10 ] polarization, [ 11 ] amplitude, [ 12–14 ] transversal shape, [ 15,16 ] and trajectory [ 17–20 ] of the electromagnetic (EM) fields. Since Capasso's group introduced the generalized laws of refraction/reflection in 2011, [ 21 ] this 2D version of metamaterials has inspired many exceptional and modern devices, typically in the field of antennas and antenna accessories.…”