Spectral and angular characteristics of dielectric resonator metasurface at optical frequencies

Zou, Longfang; López‐García, Martín; Withayachumnankul, Withawat; Shah, Charan M.; Mitchell, Arnan; Bhaskaran, Madhu; Sriram, Sharath; Oulton, Ruth; Klemm, M.

doi:10.1063/1.4901735

Cited by 19 publications

(12 citation statements)

References 25 publications

(26 reference statements)

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“…The spectral and angular characteristics of the device were then analyzed via grating and antenna theory. The far‐field behavior can be interpreted in a similar way to a conventional diffraction grating of period Λ = 2800 nm, but with the majority of the reradiated power concentrated in the first diffraction order ( m = +1) when the GST is amorphous, and in the zeroth order ( m = 0) when it is crystalline. Figure c shows the numerically computed reflectance of the three diffraction orders ( m = ± 1, m = 0), over a range of wavelengths from 1515 to 1580 nm.…”

Section: Resultsmentioning

confidence: 98%

“…Structures of this form support magnetic plasmon resonances under TM excitation, with such resonances being induced by the coupling of the electric dipole generated in the patch antenna with the bottom aluminum plane. Antisymmetric states, or curl electric fields, can therefore be induced, which result in a resonant magnetic dipole moment . The amplitude and phase response of the unit cell can therefore be tuned by engineering either its geometrical parameters or the complex refractive index of the dielectric spacer (i.e., changing its resonant frequency).…”

Section: Resultsmentioning

confidence: 99%

“…We choose here a MIM device configuration due to its ability to support antisymmetric states, and thus magnetic plasmon resonances, using dielectric spacers much smaller than the wavelength . The latter point is especially important, as PCMs need to be melted and rapidly cooled down (>20 °C ns −1 ) for a successful amorphization process, and this is facilitated by restricting the volume of material that undergoes amorphization .…”

Section: Device Design and Working Principlementioning

confidence: 99%

See 2 more Smart Citations

Nonvolatile Reconfigurable Phase‐Change Metadevices for Beam Steering in the Near Infrared

Galarreta

Alexeev

et al. 2018

Adv Funct Materials

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220

213

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. The development of flat, compact beam-steering devices with no bulky moving parts is opening up a new route to a variety of exciting applications, such as LIDAR scanning systems for autonomous vehicles, robotics and sensing, freespace, and even surface wave optical signal coupling. In this paper, the design, fabrication and characterization of innovative, nonvolatile, and reconfigurable beam-steering metadevices enabled by a combination of optical metasurfaces and chalcogenide phase-change materials is reported. The metadevices reflect an incident optical beam in a mirror-like fashion when the phase-change layer is in the crystalline state, but reflect anomalously at predesigned angles when the phase-change layer is switched into its amorphous state. Experimental angleresolved spectrometry measurements verify that fabricated devices perform as designed, with high efficiencies, up to 40%, when operating at 1550 nm. Laserinduced crystallization and reamorphization experiments confirm reversible switching of the device. It is believed that reconfigurable phase-change-based beam-steering and beam-shaping metadevices, such as those reported here, can offer real applications advantages, such as high efficiency, compactness, fast switching times and, due to the nonvolatile nature of chalcogenide phasechange materials, low power consumption.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Device Design and Working Principlementioning

confidence: 99%

See 1 more Smart Citation

Nonvolatile Reconfigurable Phase‐Change Metadevices for Beam Steering in the Near Infrared

Galarreta

Alexeev

et al. 2018

Adv Funct Materials

Self Cite

220

213

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show abstract

“…Though the application of high‐resistivity Si as resonators is just gathering steam in the terahertz region, their application for beam focusing, beam shaping, and polarization control has been reported in the microwave and optical frequency ranges . Of particular importance to this review is the fabrication steps that rely mostly on deep reactive ion etching processes used to define the structured devices, given in a later section.…”

Section: Lossless Dielectric Materialsmentioning

confidence: 99%

Dielectrics for Terahertz Metasurfaces: Material Selection and Fabrication Techniques

Ako

Upadhyay

Withayachumnankul

et al. 2019

Advanced Optical Materials

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on distinctive spectral signatures resulting from vibrational modes of covalent and hydrogen bonds. [8,[13][14][15][16] The focus on this spectrally rich region is attributed to the highly coherent and nonionizing nature of terahertz radiation, wide unallocated frequency bands, distinctive wavelengths, and their penetration through a significant depth of dielectric materials. Terahertz technology is geared toward realizing devices that can efficiently manipulate the phase, amplitude, and polarization of terahertz radiations for the above-mentioned myriad of applications.However, progress in this domain is held back by low terahertz power available from compact sources, high free-space path loss, and limited choice of materials that exhibit less absorption of terahertz waves. [17] Owing to the fact that natural materials demonstrate weak wave-matter interaction at terahertz frequencies, terahertz devices with engineered subwavelength resonant metallic inclusions on dielectric spacers have been realized, to interact strongly with an incident electromagnetic wave.In the past, metamaterials have been a promising route to building terahertz devices. These devices have in essence been engineered as 3D resonating elements that effectively manipulate both permittivity and permeability of an effective medium to couple to free space. The underlining disadvantage of these structures is the difficulty involved in the fabrication of 3D geometrical structures using standard semiconductor fabrication techniques. Standard fabrication techniques are generally amenable to 2D design with extrusion of these structures into thickness (the third, vertical dimension). Moreover, the choice and availability of dielectric materials and metals that provide sufficient interaction while retaining device efficiency has proved challenging. [13,[18][19][20] Recently, effective manipulation of electromagnetic wave has been widely demonstrated with 2D metasurfaces, which were originally employed as building blocks for 3D metamaterials. In these lower-dimension designs, effective manipulation of terahertz waves for various applications is achieved by carefully designing sub-wavelength resonant structures as is evident in published review articles. [21,22] Metasurfaces present high degree of compactness that enhances radiation efficiency. Additionally, the planar form factor of metasurfaces enables Manipulation of terahertz radiation opens new opportunities that underpin application areas in communication, security, material sensing, and characterization. Metasurfaces employed for terahertz manipulation of phase, amplitude, or polarization of terahertz waves have limitations in radiation efficiency which is attributed to losses in the materials constituting the devices. Metallic resonators-based terahertz devices suffer from high ohmic losses, while dielectric substrates and spacers with high relative permittivity and loss tangent also reduce bandwidth and efficiency. To overcome these issues, a proper choice of low loss and low relative permittivi...

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“…A large phase-shift can still be achieved by the same technology using dielectric cylinders metasurface with lower permittivities such as Si or TiO 2 . Those materials have been used to achieve near infrared/optical Mie resonances [28].…”

Section: Phase Distributionmentioning

confidence: 99%

Extremely Thin Dielectric Metasurface for Carpet Cloaking

Hsu¹,

Lepetit²,

Kanté³

2015

PIER

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Abstract-We demonstrate a novel and simple geometrical approach to cloaking a scatterer on a ground plane. We use an extremely thin dielectric metasurface to reshape the wavefronts distorted by a scatterer in order to mimic the reflection pattern of a flat ground plane. To achieve such carpet cloaking, the reflection angle has to be equal to the incident angle everywhere on the scatterer. We use a graded metasurface and calculate the required phase gradient to achieve cloaking. Our metasurface locally provides additional phase to the wavefronts to compensate for the phase difference amongst light paths induced by the geometrical distortion. We design our metasurface in the microwave range using highly sub-wavelength dielectric resonators. We verify our design by full-wave time-domain simulations using micro-structured resonators and show that results match theory very well. This approach can be applied to hide any scatterer under a metasurface of class C 1 (first derivative continuous) on a ground plane not only in the microwave regime, but also at higher frequencies up to the visible.

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Spectral and angular characteristics of dielectric resonator metasurface at optical frequencies

Cited by 19 publications

References 25 publications

Nonvolatile Reconfigurable Phase‐Change Metadevices for Beam Steering in the Near Infrared

Nonvolatile Reconfigurable Phase‐Change Metadevices for Beam Steering in the Near Infrared

Dielectrics for Terahertz Metasurfaces: Material Selection and Fabrication Techniques

Extremely Thin Dielectric Metasurface for Carpet Cloaking

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