Far-Field Subwavelength Imaging Using Phase Gradient Metasurfaces

Salami, Pooria; Yousefi, Leila

doi:10.1109/jlt.2019.2902544

Cited by 35 publications

(13 citation statements)

References 56 publications

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“…Although this is a high-resolution method, the object must be scanned and this can be time consuming especially for imaging large samples. Recently, gradient metasurfaces have been proposed to extract information from large propagating wave vectors in order to go beyond the diffraction limit 25 , 26 . Such monochromatic approaches seem limited, since all spatial information propagating away from an object is mixed in a unique wave field.…”

Section: Introductionmentioning

confidence: 99%

Far field superlensing inside biological media through a nanorod lens using spatiotemporal information

Hajiahmadi

Faraji‐Dana

Skrivervik

2021

Sci Rep

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Far field superlensing of light has generated great attention in optical focusing and imaging applications. The capability of metamaterials to convert evanescent waves to propagative waves has led to numerous proposals in this regard. The common drawback of these approaches is their poor performance inside strongly scattering media like biological samples. Here, we use a metamaterial structure made out of aluminum nanorods in conjunction with time-reversal technique to exploit all temporal and spatial degrees of freedom for superlensing. Using broadband optics, we numerically show that this structure can perform focusing inside biological tissues with a resolution of λ/10. Moreover, for the imaging scheme we propose the entropy criterion for the image reconstruction step to reduce the number of required optical transducers. We propose an imaging scenario to reconstruct the spreading pattern of a diffusive material inside a tissue. In this way super-resolution images are obtained.

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Section: Introductionmentioning

confidence: 99%

Far field superlensing inside biological media through a nanorod lens using spatiotemporal information

Hajiahmadi

Faraji‐Dana

Skrivervik

2021

Sci Rep

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“…They are more convenient (lighter and easier to fabricate) and generally have lower loss [1][2][3][4][5]. They have been used in various applications such as cloaking [6,7], illusion [8], radar cross-section (RCS) reduction, flat lens [9], thin-film solar cells [10,11], far-field sub-wavelength and computational imaging [12][13][14] among several other applications.…”

Section: Introductionmentioning

confidence: 99%

Analysis of wave scattering from 2D curved metasurfaces using Floquet and Fourier series expansions

Khatami

Dehmollaian

Yousefi

2021

IET Microwaves Antenna & Prop

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An efficient technique for calculating the scattering from curved metasurfaces using the extinction theorem in conjunction with the Floquet and Fourier series expansions is presented. Here, we treat the two-dimensional metasurfaces that have transversal polarizabilities with no variation along the y-axis. The boundary conditions at the metasurface are given by the generalized sheet transition conditions (GSTCs) whose susceptibilities are given in an arbitrary local coordinate system. First, we use the extinction theorem to provide integral equations of the scattering problem. The integral equations involve the Green's functions, tangential electric and magnetic fields and their normal derivatives in regions above and below the metasurface. Then, we employ the Floquet theorem that gives us the analytical periodic Green's functions of each region. Next, we employ the Fourier theorem to expand the tangential fields in terms of unknown Fourier coefficients. The GSTCs and the integral equations provide equations to be solved for the unknowns. The method can calculate scattering from both periodic and non-periodic metasurfaces. The technique is used to analyse different applied problems such as carpet cloaking, illusion, and radar echo width reduction. The method is fast and accurate and can efficiently treat metasurfaces with electrically large curved geometries with dimensions as large as 120 times the wavelength.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…Metasurfaces, which are two‐dimensional version of metamaterials [20–23], are able to apply abrupt changes of phase, amplitude, and polarisation, to the incident wave [24–27]. This ability of metasurfaces has been used in different applications such as increasing efficiency of thin film solar cells [28, 29], developing flat lenses [30], designing photonic topological insulators [31], and enhancing absorption in infrared detectors [32].…”

Section: Introductionmentioning

confidence: 99%