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.
Highlights
The study of analog computing scheme has been one of the hottest areas of the optical domain over the past few years and despite the prevalence of traditional digital integrated electronic-based technologies, it has had a profound impact across the modern photonic requisitions [1]
The prominent wave-matter-interacting capabilities of metamaterial family suggest a variety of intriguing wave-based phenomena such as all-optical logics [12], all-optical differentiators and integrators [13,14,15] and some more sophisticated computing operators, such as differential and integro-differential equation solvers or/and image processing tools at the miniaturized hardware level [4, 6, 7, 9]
We have proposed the concept of a bianisotropic metasurface with normal polarizations potentially capable of realizing the Green’s function (GF) associated with general linear mathematical operations
Summary
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. 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. This work opens a new route for designing ultra-thin devices executing parallel and accelerated optical signal/image processing
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