Integration in analog optical computing using metasurfaces revisited: toward ideal optical integration

Babashah, Hossein; Kavehvash, Zahra; Koohi, Somayyeh; Khavasi, Amin

doi:10.1364/josab.34.001270

Cited by 33 publications

(24 citation statements)

References 17 publications

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“…As can be seen, while the integrator has worked well to retrieve the non-zero spatial harmonics of the input field, it fails to retrieve the zero harmonic or the DC part. A modified method [14], can be used to improve the accuracy of integration when the metasurface is fed by signals rich in low-frequency contents. As the inset of Fig.…”

Section: A Single Mathematical Transformation With Polarization-indementioning

confidence: 99%

“…In the spatial domain, such computing enables massively parallel processing of entire images with no energy cost, which provides significant advantages against standard digital processing of images [13]. To go beyond the drawbacks of temporal analog computing, two metasurface and Green's Function (GF) approaches have emerged for performing metamaterialbased spatial analog computations [13][14][15]. In the first method in which the operator of choice is implemented by a thin planar metamaterial in Fourier domain, the preliminary necessity of two additional sub-blocks to apply Fourier and Inverse Fourier Transforms, implies a significant increase in the overall size of system.…”

Section: Introductionmentioning

confidence: 99%

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Generalized Optical Signal Processing Based on Multioperator Metasurfaces Synthesized by Susceptibility Tensors

et al. 2019

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This paper theoretically proposes a multichannel functional metasurface computer characterized by Generalized Sheet Transition Conditions (GSTCs) and surface susceptibility tensors. The study explores a polarization-and angle-multiplexed metasurfaces enabling multiple and independent parallel analog spatial computations when illuminated by differently polarized incident beams from different directions. The proposed synthesis overcomes substantial restrictions imposed by previous designs such as large architectures arising from the need of additional subblocks, slow responses, and most importantly, supporting only the even reflection symmetry operations for normal incidences, working for a certain incident angle or polarization, and executing only single mathematical operation. The versatility of the design is demonstrated in a way that an ultra-compact, integrable and planar metasurface-assisted platform can execute a variety of optical signal processing operations such as spatial differentiation and integration. It is demonstrated that a metasurface featuring nonreciprocal property can be thought of as a new paradigm to break the even symmetry of reflection and perform both even-and odd-symmetry mathematical operations at normal incidences. Numerical simulations also illustrate different aspects of multichannel edge detection scheme through projecting multiple images on the metasurface from different directions. Such appealing findings not only circumvent the major potential drawbacks of previous designs but also may offer an efficient, easy-to-fabricate, and flexible approach in wave-based signal processing, edge detection, image contrast enhancement, hidden object detection, and equation solving without any Fourier lens.

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Section: A Single Mathematical Transformation With Polarization-indementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Generalized Optical Signal Processing Based on Multioperator Metasurfaces Synthesized by Susceptibility Tensors

et al. 2019

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“…They can alter the amplitude, phase, and polarization responses of the incident waves, and thus offer ideal toolkit to realize numerous functions, such as polarization conversion, [ 22 ] subwavelength imaging, [ 23 ] and hologram generation. [ 24,25 ] Since the advent of artificial surfaces, a series of metasurface‐based signal processing devices, such as integrator, [ 26 ] equation solver, [ 27 ] and spatial filter, [ 28 ] have been implemented in spatial domain and considered as promising candidates for future optical analogue computing systems. Recently, the time‐space‐coding metasurfaces with periodically varying reflection or transmission coefficients have been proposed to trigger enhanced nonlinearities during wave–matter interactions, thereby boosting the efficiency of spatial mixing and harmonic generation.…”

Section: Introductionmentioning

confidence: 99%

Metasurface‐Based Spatial Phasers for Analogue Signal Processing

Chen

Cheng

Xia

et al. 2020

Advanced Optical Materials

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A dispersive delay structure, or phaser, is an integral part of analogue signal processor. A phaser is a circuit, whose group delay can be engineered to obtain the desired response as a function of frequency. Traditionally, phasers have been implemented in circuits or waveguide structures, but they can never deal with electromagnetic waves in free space due to limitation of natural materials. To resolve this drawback, a novel metasurface‐based structure, spatial phaser, for analogue signal processing in the spatial domain is proposed. A general design theory is put forward to realize the spatial phaser for manipulating the dispersive delay of electromagnetic waves. To demonstrate this method, three spatial phasers with different group‐delay responses are elaborately devised and a prototype that exhibits a positive‐triangular group delay from 8 to 10 GHz is fabricated. The experimental and simulation results show good agreement. This work will facilitate the development of real‐time analogue signal processing in spatial domain for applications in radars, electronic countermeasures, and other related areas.

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“…Based on this concept, many works on mathematical metamaterials have been reported. [ 33–35 ] In the study by AbdollahRamezani et al., [ 33 ] a computing system consisting of graphene‐based metasurface was proposed to perform the differentiation and integration theoretically, in which its structure is more compact than that in the study by Silva et al. [ 32 ] A modified optical integrator composed of metamaterial blocks was presented, which has superior performance in the case of input signals with considerable low‐frequency contents.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Operations of Transmissive Near Fields Controlled by Metasurface with Phase and Amplitude Modulations

Bao

et al. 2020

Annalen der Physik

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Metasurfaces show great potential due to their powerful ability to manipulate electromagnetic waves as desired, which has been widely investigated in the microwave, terahertz, infrared, and visible regimes. Here, it is proposed to control near‐field distributions through use of a metasurface with both amplitude and phase modulations. A C‐shaped particle is designed to provide stable and continuous amplitude and phase profiles independently of transmitted waves by varying its opening and orientation angles. Benefiting from both amplitude and phase modulations on the metasurface, differentiation and integration on electric‐field distributions can be achieved by changing the arrangements of complex coefficients on the metasurface. Besides, the differential operation can be utilized to show the edges of predesigned electric‐field distributions. It is believed that the proposed method will accelerate the pace of metasurfaces towards many applications by engineering and operating the near‐field distributions.

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Integration in analog optical computing using metasurfaces revisited: toward ideal optical integration

Cited by 33 publications

References 17 publications

Generalized Optical Signal Processing Based on Multioperator Metasurfaces Synthesized by Susceptibility Tensors

Generalized Optical Signal Processing Based on Multioperator Metasurfaces Synthesized by Susceptibility Tensors

Metasurface‐Based Spatial Phasers for Analogue Signal Processing

Mathematical Operations of Transmissive Near Fields Controlled by Metasurface with Phase and Amplitude Modulations

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