Photonic crystal slab Laplace operator for image differentiation

Guo, Cheng; Xiao, Meng; Minkov, Momchil; Shi, Yu; Fan, Shanhui

doi:10.1364/optica.5.000251

Cited by 214 publications

(140 citation statements)

References 35 publications

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“…From a general viewpoint, the transfer function required to solve equations (1), (2) has an asymmetric behavior (no odd-or even-symmetry) with respect to k x variable. Accordingly, the current GF-based analog computing proposals fail to solve these equations for input fields coming from boresight direction, as they can realize transfer functions with only even-symmetry mathematical operators for normal incidences [20,21]. There are three important points: Firstly, the GF-based CODE and/or CIDE solving optical devices have not been reported, yet.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

“…There are three important points: Firstly, the GF-based CODE and/or CIDE solving optical devices have not been reported, yet. Secondly, the current capabilities for realization of GF-based computational metamaterials [20,21] can only deal with particular cases of CIDE and CODE, albeit, for oblique processing channels. Thirdly, finding suitable meta-atoms to realize such complex spatial transfer functions will be very sophisticated and time-consuming if we deal with the problem by trial and error.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

“…Albeit, there are metamaterial designs based on GF approach proposed for image processing [18]. A multitude of attempts have been also devoted to advance the functionality of all-optical signal processing architectures where several theoretical/ experimental demonstrations have been lately published [20,21]. For instance, the authors in [20] have demonstrated that the Laplacian operation can be implemented by photonic crystal slab device in the transmission mode.…”

Section: Introductionmentioning

confidence: 99%

“…A multitude of attempts have been also devoted to advance the functionality of all-optical signal processing architectures where several theoretical/ experimental demonstrations have been lately published [20,21]. For instance, the authors in [20] have demonstrated that the Laplacian operation can be implemented by photonic crystal slab device in the transmission mode. Zhu et al have shown that the interference effects associated with surface plasmon excitations at a single metaldielectric interface can perform spatial differentiation and edge detection without any Fourier lens [21].…”

Section: Introductionmentioning

confidence: 99%

“…Roberts et al have provided a framework to illustrate the capacity of spatially dispersive modes in uniform metasurfaces for modifying or enhancing the input image contrast and manipulating the spatial content of the incident field in analog optical information processing [22]. In a nutshell, however, all existing optical processing proposals still suffer from slow responses [11], supporting only the even symmetry operations for normal incidences [20,21], working for a certain incident angle or polarization [16,21], and solving only one integro-differential equation [3,10]. However, to the best of authors' knowledge, realizing such advanced optical signal processing functions via the GF approach has not been addressed, yet.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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

et al. 2019

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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.

show abstract

Section: Theoretical Frameworkmentioning

confidence: 99%

Section: Theoretical Frameworkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

et al. 2019

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Spiral Metalens for Phase Contrast Imaging

Kim

Lee

Sung

et al. 2021

Adv Funct Materials

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Spiral phase contrast imaging offers an excellent opportunity to observe nonlabeled biological samples with slight variations in refractive index or thickness. However, the overall system covering previous works is still complex and bulky, hindering miniaturization and compatibility with conventional systems. Furthermore, high-resolution imaging, particularly for observing biological specimens such as cellular structures, requires several refractive optical elements like objectives and relay optics which dramatically increases the system form factor. Here, it is demonstrated that a metalens, in which the phase profile is a sum of the hyperbolic phase and spiral phase with a topological charge of 1, performs 2D isotropic edge-enhanced imaging. The metalens achieves a submicrometer resolution of up to 0.78 µm operated under visible broadband range in conjunction with a compact form factor. Furthermore, experiments with biological samples can additionally prove the feasibility of practical usage. Capitalizing on compactness and high-resolution characteristics, it is believed that the scheme provides a stepping stone to biomedical imaging technologies and analog computing.

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Nonlinear Computational Edge Detection Metalens

Zhou

Chen

et al. 2022

Adv Funct Materials

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Optical image processing and computing systems provide supreme information processing rates by utilizing parallel optical architectures. Existing optical analog processing techniques require multiple devices for projecting images and executing computations. In addition, those devices are typically limited to linear operations due to the time-invariant optical responses of the building materials. In this work, a single metalens with an illumination intensity dependent coherent transfer function (CTF) is proposed and experimentally demonstrated, which performs varying computed imaging without requiring any additional optical components. The metalens consisting of nanoantenna structures with a static geometric phase and a nonlinear metallic quantum well layer offering an intensity-dependent dynamic phase results in a continuously tunable CTF. The approach allows for a weighted summation of two designed functions based on the metalens design, which potentially enables all optical computations of complex functions. The nonlinear metalens may lead to important applications in optical neural networks and parallel analog computing.

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Photonic crystal slab Laplace operator for image differentiation

Cited by 214 publications

References 35 publications

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

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

Spiral Metalens for Phase Contrast Imaging

Nonlinear Computational Edge Detection Metalens

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