Mechanism Behind Angularly Asymmetric Diffraction in Phase-Gradient Metasurfaces

Cao, Yanyan; Fu, Yangyang; Zhou, Qingjia; Ou, Xin; Gao, Lei; Chen, Huanyang; Xu, Yadong

doi:10.1103/physrevapplied.12.024006

Cited by 43 publications

(30 citation statements)

References 27 publications

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“…For example, studies have reported asymmetric optical properties for different directions by optimizing the geometric conditions of metasurfaces, such as an asymmetricdiffraction optical device using a difference in phase delay caused by tuning the parameter of the depth of the groove [38] or an asymmetric propagation device using the difference in intensity and phase delay of electromagnetic waves caused by the lossy planar chiral structure [39]. Additionally, asymmetric transmission studies using a nanopolymerization technique, such as multichannel polarization conversion elements using anisotropic diffraction stripe structures in which nematic molecule materials are homogeneously arranged, have been reported [40].…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Diffraction in Plasmonic Meta-Gratings Using an IT-Shaped Nanoslit Array

Jeong

Moon

Lee

2021

Sensors

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Diffraction is a fundamental phenomenon that reveals the wave nature of light. When a plane wave is transmitted or reflected from a grating or other periodic structures, diffracted light waves propagate at several angles that are specified by the period of the given structure. When the optical period is shorter than the wavelength, constructive interference of diffracted light rays from the subwavelength-scale grating forms a uniform plane wave. Many studies have shown that through the appropriate design of meta-atom geometry, metasurfaces can be used to control light properties. However, most semitransparent metasurfaces are designed to perform symmetric operation with regard to diffraction, meaning that light diffraction occurs identically for front- and back-side illumination. We propose a simple single-layer plasmonic metasurface that achieves asymmetric diffraction by optimizing the transmission phase from two types of nanoslits with I- and T-shaped structures. As the proposed structure is designed to have a different effective period for each observation side, it is either diffractive or nondiffractive depending on the direction of observation. The designed structure exhibits a diffraction angle of 54°, which can be further tuned by applying different period conditions. We expect the proposed asymmetric diffraction meta-grating to have great potential for the miniaturized optical diffraction control systems in the infrared band and compact optical diffraction filters for integrated optics.

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Section: Introductionmentioning

confidence: 99%

Asymmetric Diffraction in Plasmonic Meta-Gratings Using an IT-Shaped Nanoslit Array

Jeong

Moon

Lee

2021

Sensors

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“…Therefore, these AMs for AT are generally composed of multiple unit cells, which not only adds the design complexities but also poses a challenge for sample fabrication in higher frequencies [23]. Meanwhile, more unit cells in AMs can bring more sound absorption due to multiple reflection effect [24,25], which may reduce the performance of AT. Therefore, AMs with simplified design is extremely desirable to control wave propagation, in particular, to realize AT.…”

Section: Introductionmentioning

confidence: 99%

Controllably asymmetric beam splitting via gap-induced diffraction channel transition in dual-layer binary metagratings

Tao

Song

et al. 2020

Front. Phys.

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In this work, we designed and studied a feasible dual-layer binary metagrating, which can realize controllable asymmetric transmission and beam splitting with nearly perfect performance. Owing to ingenious geometry configuration, only one meta-atom is required to design for the metagrating system. By simply controlling air gap between dual-layer metagratings, high-efficiency beam splitting can be well switched from asymmetric transmission to symmetric transmission. The working principle lies on gap-induced diffraction channel transition for incident waves from opposite directions. The asymmetric/symmetric transmission can work in a certain frequency band and a wide incident range. Compared with previous methods using acoustic metasurfaces, our approach has the advantages of simple design and tunable property and shows promise for applications in wavefront manipulation, noise control and acoustic diode.

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“…In particular, for high-order PGM diffractions, m leads to a new set of diffraction equations expressed as [21]: , ( ) , ( ) Gp   is the reciprocal lattice vector, n is the diffraction order, and L=m-n is the propagation number of multiple internal total reflections inside the PGM, i.e., the number of times that the wave travels inside the PGM. Such an additional process of multiple internal total reflections can lead to angularly asymmetric absorption [22][23][24][25] in a PGM with some loss, because the absorption efficiency is also related to m. Therefore, in addition to the phase gradient, the integer number of unit cells m in a supercell is another degree of freedom that can be employed to control the light propagation.…”

Section: Introductionmentioning

confidence: 99%

Phase-Gradient Metasurfaces Based on Local Fabry–Pérot Resonances

Cao¹,

Yu²,

Fu³

et al. 2020

Chinese Phys. Lett.

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In this work, we present a new mechanism for designing phase-gradient metasurfaces (PGMs) to control an electromagnetic wavefront with high efficiency. Specifically, we design a transmission-type PGM, formed by a periodic subwavelength metallic slit array filled with identical dielectrics of different heights. It is found that when Fabry–Pérot (FP) resonances occur locally inside the dielectric regions, in addition to the common phenomenon of complete transmission, the transmitted phase differences between two adjacent slits are exactly the same, being a nonzero constant. These local FP resonances ensure total phase shift across a supercell, fully covering a range of 0 to 2π, satisfying the design requirements of PGMs. Further research reveals that, due to local FP resonances, there is a one-to-one correspondence between the phase difference and the permittivity of the filled dielectric. A similar approach can be extended to the reflection-type case and other wavefront transformations, creating new opportunities for wave manipulation.

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Mechanism Behind Angularly Asymmetric Diffraction in Phase-Gradient Metasurfaces

Cited by 43 publications

References 27 publications

Asymmetric Diffraction in Plasmonic Meta-Gratings Using an IT-Shaped Nanoslit Array

Asymmetric Diffraction in Plasmonic Meta-Gratings Using an IT-Shaped Nanoslit Array

Controllably asymmetric beam splitting via gap-induced diffraction channel transition in dual-layer binary metagratings

Phase-Gradient Metasurfaces Based on Local Fabry–Pérot Resonances

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