Directional conversion of a THz propagating wave into surface waves in deformable metagratings

Liu, Jiaming; Xu, Fang; He, Fei; Yin, Shengqi; Lyu, Wen; Geng, Hua; Deng, Xiaojiao; Zheng, Xiaoping

doi:10.1364/oe.431817

Cited by 11 publications

(8 citation statements)

References 39 publications

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“…This is because the key mechanism of our work is the use of PGM to realize the efficient conversion of the incident plane waves to surface waves. Many previous works have been reported to achieve this aim using different PGM structures [34,42,43]. Therefore, in principle, the other PGM structures can also realize the results of this paper.…”

Section: Discussionmentioning

confidence: 72%

Controlling the light diffraction through a single subwavelength metallic slit via phase gradient

Gao

et al. 2023

New J. Phys.

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In this work, we show that the concept of phase gradient metasurfaces provides a versatile way to control the diffraction of light through small holes or slits. As an example, we consider a single subwavelength metallic slit surrounded by air grooves of gradient depth that induces the expected phase gradient. It is found that for normal incident light, the phase gradient can enable unidirectional excitation of surface plasmons, which flows directionally towards the slit, resulting in extraordinary optical transmission beyond that in conventional ways. Using this scheme, a unidirectional radiation of an optical dipole located inside the slit can be obtained when different phase gradients are applied to both sides of the metal plate.

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Section: Discussionmentioning

confidence: 72%

Controlling the light diffraction through a single subwavelength metallic slit via phase gradient

Gao

et al. 2023

New J. Phys.

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“…In order to break this limitation, a metagrating with unit-cell containing three cylinders is designed. Light transmission consequently follows the grating formula m λ = d false( n t nobreak0em0.25em⁡ sin nobreak0em.25em⁡ θ t − n i nobreak0em0.25em⁡ sin nobreak0em.25em⁡ θ i false) where m is the diffraction order, d is the grating periodicity along the diffraction direction, θ i and θ t are the angle of incidence and refraction, and n i and n t are the refractive indices of the two media. With the normal incident light beam, the design process of the unit cell in the metagrating is as follows.…”

Section: Resultsmentioning

confidence: 99%

“…35 In order to break this limitation, a metagrating with unit-cell containing three cylinders is designed. Light transmission consequently follows the grating formula 21 m d n n ( sin sin )…”

Section: Resultsmentioning

confidence: 99%

“…It can achieve flexibly and highly efficient beam manipulation that is simultaneously low requirement for advanced manufacturing technology; thus it has shown great potential. The exploration of metagrating devices almost exists in the entire electromagnetic spectrum, which is used in various fields such as communication, sensing, and imaging . With the development of tunable technology, the design of metagrating realizes the switch of specific functions under different excitation factors.…”

Section: Introductionmentioning

confidence: 99%

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All-Dielectric Tunable Terahertz Metagrating for Diffraction Control

Shi

Gao

Jia

et al. 2022

ACS Appl. Mater. Interfaces

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Recently, tunable metagratings have attracted substantial attention in manipulating the diffraction of electromagnetic waves with considerable flexibility, but they are usually limited to inherent ohmic loss due to the metal layers. The alldielectric schemes can address this issue, but its design and optimization remain challenging in the terahertz regime, especially in the 6G communication window. In this work, an all-dielectric tunable terahertz metagrating is demonstrated in theoretical and experimental investigations. The metagrating operating in the 6G communication window bends the electromagnetic waves beam into the T −1 diffraction order by optimizing the unit cell. In the experiments, more than 72.46% of the transmitted energy is concentrated in the desired diffraction order for p-polarized light and more than 66.60% for s-polarized light, which agrees well with the theoretical design. The tunability by angular deflection is reported in this all-dielectric metagrating. Then, based on the all-dielectric metagrating arrays, a metalens with numerical aperture of NA = 0.39 at 0.14 THz is demonstrated. The subwavelength scale focal spot is obtained as 2.0 mm × 2.0 mm with the focusing distance of 117.8 mm. Imaging capability of the metalens is performed utilizing the transmission imaging manner. The measured and anticipated results are satisfactorily congruous with one another, which could validate our design. This work paves the way toward designing highly efficient and tunable devices with potential applications in terahertz communications, sensors, and super-resolution imaging.

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“…However, just to give the readers a flavor of the broad scope of research areas that have employed this concept, here we list a few of the main applications that have been introduced in the past few years. Metagratings have been employed for lensing [52], [65], [85]- [87], holograms [88], [89], generation of vortex beams [90], [91], sensors [92], [93], high-Q resonators [94], ultra-narrowband absorbers [95], [96], power splitters [97]- [99], spectrum splitters [100], optical computing [101], [102], engineering reactive near field profiles [103], waveguiding for mode conversion and elimination of reflections at the bends [104], [105], light emitting devices [106], metrology [107], photovoltaics [108], retroreflectors [109], space-to-surface wave converting surfaces [110], and waterborne acoustics [79].…”

Section: Metagratings For Various Applicationsmentioning

confidence: 99%

Metagratings for Efficient Wavefront Manipulation

Ra’di

Alù

2022

IEEE Photonics J.

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Recently, it was revealed that conventional gradient metasurfaces are fundamentally limited on their overall efficiency to reroute the impinging waves towards arbitrary directions in reflection and transmission. Their efficiency is particularly limited for extreme wavefront transformations. In addition, due to the fastly varying impedance profiles that these surfaces require, they usually need high-resolution fabrication processes, limiting their applicability and overall bandwidth of operation. To address these issues, the concept of metagrating was recently introduced, enabling engineered surfaces capable of manipulating light with unitary efficiency even in the limit of extreme wavefront manipulation. Metagratings are periodic or locally periodic arrays operated in the few-diffraction order regime. Their unit cell contains carefully designed scatterers that, in contrast with conventional metasurfaces, do not need to support a continuous gradient of surface impedance, and consequently are far simpler to fabricate and can afford broader bandwidths because of the larger footprint of the constituent elements. Tailoring the coupling towards the few available diffraction channels, metagratings enable wavefront transformations with high efficiency. In this paper, we review the physical mechanisms behind the functionality of metagratings and provide an overview and outlook of the recent progress in this field of science and technology.

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Directional conversion of a THz propagating wave into surface waves in deformable metagratings

Cited by 11 publications

References 39 publications

Controlling the light diffraction through a single subwavelength metallic slit via phase gradient

Controlling the light diffraction through a single subwavelength metallic slit via phase gradient

All-Dielectric Tunable Terahertz Metagrating for Diffraction Control

Metagratings for Efficient Wavefront Manipulation

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