Spin-selected focusing and imaging based on metasurface lens

Wang, Sen; Wang, Xinke; Kan, Qiang; Ye, Jiasheng; Feng, Shengfei; Sun, Wenfeng; Han, Peng; Qu, Shiliang; Zhang, Yan

doi:10.1364/oe.23.026434

Cited by 77 publications

(57 citation statements)

References 35 publications

(52 reference statements)

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“…The experimental results show that the normally incident terahertz wave could be deflected to an angle as large as 72° with 40% efficiency, which is significantly better than the previously reported results realized by the conventional reflectarray even at microwave frequency 42. Owning to the existence of Fourier transform relation between the coding pattern and far‐field pattern, the coding metasurfaces can be studied from a fully digital perspective, enabling more versatile manipulations to scattering patterns, and therefore have the potential to be applied in many terahertz devices such as metalens,4, 43 metaholography,44, 45 and spoof surface plasmon polariton devices 9, 12, 46…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Convolution Operations on Coding Metasurface to Reach Flexible and Continuous Controls of Terahertz Beams

et al. 2016

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The concept of coding metasurface makes a link between physically metamaterial particles and digital codes, and hence it is possible to perform digital signal processing on the coding metasurface to realize unusual physical phenomena. Here, this study presents to perform Fourier operations on coding metasurfaces and proposes a principle called as scattering‐pattern shift using the convolution theorem, which allows steering of the scattering pattern to an arbitrarily predesigned direction. Owing to the constant reflection amplitude of coding particles, the required coding pattern can be simply achieved by the modulus of two coding matrices. This study demonstrates that the scattering patterns that are directly calculated from the coding pattern using the Fourier transform have excellent agreements to the numerical simulations based on realistic coding structures, providing an efficient method in optimizing coding patterns to achieve predesigned scattering beams. The most important advantage of this approach over the previous schemes in producing anomalous single‐beam scattering is its flexible and continuous controls to arbitrary directions. This work opens a new route to study metamaterial from a fully digital perspective, predicting the possibility of combining conventional theorems in digital signal processing with the coding metasurface to realize more powerful manipulations of electromagnetic waves.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Convolution Operations on Coding Metasurface to Reach Flexible and Continuous Controls of Terahertz Beams

et al. 2016

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“…4a-b, for the singlefocus lens, the transmitted wave is focused at 6 mm away from the incident plane, which consists with the designed value. And the focusing of the transmitted wave is not affected by the chirality of the circularly polarized light, which is clearly distinct from the dual-polarity [17] or spinselected [24] metasurface lens reported. This property arises from the fact that the π phase difference between α = −45 • and α = 45 • slit for the LCP light is equal to the −π phase difference for the RCP light.…”

Section: Resultsmentioning

confidence: 66%

Metasurface Lens for both Surface Plasmon Polaritons and Transmitted Wave

Wang

et al. 2016

Plasmonics

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Metasurface lenses which could simultaneously focus both surface plasmon polaritons (SPPs) and transmitted wave are designed. This kind of device is composed of slit antennas and is optimized with the simulated annealing algorithm to realize a single-focus or double-focus lens. Interestingly, the focusing of SPPs is polarization dependent while the focusing of the transmitted wave is immune from the polarization of incident light. The proposed methodology may inspire more designs of device steering both surface wave and transmitted wave.

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“…By integrating the phase gradients along the two directions with a dynamic phase lens, the scattered LCP and RCP parts are not only separated, but also focused to different positions . Spin‐dependent splitting and focusing are also realized in the THz range, where the phase gradients along both directions are achieved by the distribution of the antennas . Since the LCP and RCP images of the target object can be simultaneously formed, interesting functionalities such as the circular dichroism measurement can be performed with a simplified imaging system.…”

Section: Wavefront Control In the Free Spacementioning

confidence: 99%

Geometric Metasurfaces for Ultrathin Optical Devices

Wen

Yue

Liu

et al. 2018

Advanced Optical Materials

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occurring materials, it is difficult to further reduce the thickness of optical elements based on such a design theory. [1] Metamaterials are artificially structured materials which attain their properties from the unit structures rather than the constituent materials, [2] so their optical properties such as the effective electric permittivity and the magnetic permeability can be tuned accordingly. [3] To overcome the fabrication difficulties of metamaterials working in the optical range, a 2D metamaterial, or metasurface has been developed, which consists of a layer of optical antennas to locally modify the phase, amplitude, and polarization of the scattered light. [1b,4] Optical antennas are typically made of metals or high refractive index dielectrics, which can be fabricated through standard nanofabrication process, such as electron beam lithography, liftoff process, focused ion beam milling, or reactive ion etching, thus the complexity of the fabrication is greatly reduced in comparison with that for their 3D counterparts. Besides, metasurfaces can change the properties of the scattered light by using antennas with a dimension smaller than the operating wavelength, which exhibits high resolution and can avoid the higher diffraction orders of the traditional diffractive optical devices. In addition, the thickness of the metasurface is much smaller than the incident wavelength which makes them practical for device miniaturization and system integration.Metasurfaces are generally divided into two categories based on their mechanisms: [1a] the one based on the dispersion of antenna resonance and the one based on the Pancharatnam-Berry phase, namely, geometric phase. [5] The former relies on the delicate design of antenna geometry to obtain the desired phase delay of the scattered light. For example, the V-shaped antennas with various arm lengths and opening angles can provide phase gradient to the cross-polarized light, which verifies the generalized laws of reflection and refraction. [6] In contrast, the latter usually contains antennas with the same structure but spatially variant orientations. [7] Each antenna can be regarded as an anisotropic scatterer, which converts part of the incident circularly polarized (CP) light to its opposite helicity with a geometric phase ± 2ψ. The symbol ψ represents the orientation angle of the antenna, with + sign for the conversion from left-handed circularly polarized (LCP) light to righthanded circularly polarized (RCP) light, and the − sign for RCP to LCP light. Thus, a sampled phase function can be imparted to the scattered light from an array of antennas with designed Metasurfaces, planar metamaterials consisting of a single layer or several layers of artificial structures, not only form the basis for fundamental physics research but also have considerable technological significance. Metasurfaces can locally modify the optical property within a subwavelength range, which can facilitate device miniaturization and system integration. Metasurfaces have shown extraordin...

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Spin-selected focusing and imaging based on metasurface lens

Cited by 77 publications

References 35 publications

Convolution Operations on Coding Metasurface to Reach Flexible and Continuous Controls of Terahertz Beams

Convolution Operations on Coding Metasurface to Reach Flexible and Continuous Controls of Terahertz Beams

Metasurface Lens for both Surface Plasmon Polaritons and Transmitted Wave

Geometric Metasurfaces for Ultrathin Optical Devices

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