An ultrathin terahertz lens with axial long focal depth based on metasurfaces

Jiang, Xiaoyan; Ye, Jiasheng; He, Jingwen; Wang, Xinke; Hu, Dan; Feng, Shengfei; Kan, Qiang; Zhang, Yan

doi:10.1364/oe.21.030030

Cited by 114 publications

(73 citation statements)

References 29 publications

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“…Plasmonic resonance in a metal-dielectric structure has been widely explored to implement resonant units with a wide range of phase change and a nearly constant amplitude [2][3][4][5][6][7][8][9][10][11][12][13][14]. These resonant units are usually much smaller than the operational wavelength.…”

Section: Tunable Resonancementioning

confidence: 99%

“…Metasurfaces have also been proposed to implement metalenses [7][8][9][10], with the phase distribution on the metasurface…”

Section: Metasurface For Beam Focusingmentioning

confidence: 99%

“…Metasurfaces comprised of nanoantenna phased-array have been investigated for holography, quarter-waveplate, metalenses, and meta-mirrors [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Metasurfaces have also been proposed to implement metalenses working in different bands [7][8][9][10]. Near-infrared metalenses and axicons have been proposed at λ ∼ 1.5 µm [7,8] and 1 THz [10].…”

Section: Introductionmentioning

confidence: 99%

“…Near-infrared metalenses and axicons have been proposed at λ ∼ 1.5 µm [7,8] and 1 THz [10]. In [11], an antenna element has been proposed to generate a local transmittance of e jφ on a metasurface.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Microwave Tunable Metasurfaces Implemented With Ferroelectric Materials and Periodical Copper Wires

Yeh¹,

Kiang²

2014

PIER M

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Abstract-A tunable metasurface composed of multiple resonant units is proposed, with each unit containing a block of SrTiO 3 ferroelectric and a periodical copper-wire structure. The local transmission coefficient of the metasurface can be controlled by tuning the permittivity of SrTiO 3 via a bias voltage. A tunable metasurface is simulated to steer the beam direction at the angles of 30 • and 14.47 • , respectively. Another one is simulated to focus the wave beam at the focal lengths of 2λ 0 and 4λ 0 , respectively.

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Section: Tunable Resonancementioning

confidence: 99%

“…Metasurfaces have also been proposed to implement metalenses [7][8][9][10], with the phase distribution on the metasurface…”

Section: Metasurface For Beam Focusingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Microwave Tunable Metasurfaces Implemented With Ferroelectric Materials and Periodical Copper Wires

Yeh¹,

Kiang²

2014

PIER M

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A Broadband Metasurface‐Based Terahertz Flat‐Lens Array

Qiu

Zhang

et al. 2015

Advanced Optical Materials

192

110

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COMMUNICATIONIn this article, we introduce a metasurface-based broadband fl at-lens array functioning in the terahertz regime. Being functional devices consisted of a number of regularly arranged lenslets, lens arrays not only possess superior focusing and imaging functionalities but also have many intriguing characteristics beyond what a single lens would approach. Lens arrays have been widely used in photography, communications, and photomemory. For instance, ideal wavefront measurement method can be achieved by combining lens array with Hartmann-Shack sensor at visible light frequencies. [ 31 ] Besides, they are widely used in digital cameras to increase the fi lling factor of the detector array. In the terahertz regime, the lens array is one of the key components in terahertz cameras and terahertz communication systems. Generally, by employing a terahertz detector behind each lenslet, the lens array enables multipixel receiving. Moreover, lens arrays with tunable focal length have potential applications in 2D and 3D switchable displays and tunable photonic devices. However, conventional fabrication approaches including direct laser writing in photoresist [ 32 ] and silicon machining technique [ 33 ] are complex and very costly due to requiring interconnections, storage systems, and photovoltaic photography. There is a strong demand for a low-cost, broadband, and fl exible terahertz lens array for various applications of terahertz technology. Here, by adopting the C-shape split-ring resonators (CSRRs) with phase discontinuities, we proposed a metasurface-based terahertz fl at-lens array. We experimentally examined and explored the unique characteristics of the fl atlens array by using near-fi eld scanning terahertz microscopy (NSTM). We show that the proposed fl at-lens array is fl exible, robust, and broadband. Compared to the lens arrays developed with conventional approaches, the metasurface-based lens array is much thinner and lighter, more fl exible, and has broader numerical aperture (NA) variation range. The proposed metasurface-based fl at-lens array paves a novel way to planar terahertz device designs and may have important applications in terahertz imaging and communications.To realize the focusing functionality using metasurfaces, it is crucial to achieve a group of unit elements that enable abrupt phase shift covering a 2π range and a nearly constant transmission amplitude simultaneously. Ultrathin fl at lenses based on metasurfaces have already been demonstrated using 2D V-shaped or rotated bar antennas. [20][21][22][23] Here, the CSRR which reveals strong response to the terahertz radiation is designed as the basic unit structures, [ 34 ] as shown in Figure 1 a. The symmetry lines of the CSRRs are oriented ±45° with respect to the x -axis. Due to structure symmetry, when the incidence polarization is along the x -axis, it partially converts into the y -polarized component in the resonance frequencies range. This feature essentially lies on the superposition of different resonance Recently, growin...

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Longitudinal Multifoci Metalens for Circularly Polarized Light

Chen

Mehmood

et al. 2015

Advanced Optical Materials

213

120

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COMMUNICATION metalenses, [ 27,28 ] aberration-free quarter-wave plates (QWPs), [ 29 ] spin-hall effect of light and spin-controlled photonics, [ 30,31 ] unidirectional surface plasmon polariton excitation [31][32][33][34] and 3D optical holography. [35][36][37][38] As a fundamental optical device, a lens lies in the heart of many important applications in various scientifi c communities such as physics, optics, biology, medicine, and security. People have been fascinated by using different technologies to develop lenses with unusual features, such as ultrathin metalenses based on metasurface [ 27,28,39,40 ] and multifoci diffractive lenses [ 41,42 ] based on diffraction optics. A multifoci diffractive lens allows a single incident beam to focus at different positions along the longitudinal axis or along the transverse direction, which has been widely used in imaging systems, detectors, optical data storage, laser printing and optical freespace communications. [41][42][43][44] However, all the polarization states of the focal points are the same as that of the incident light. Moreover, the traditional method to design and fabricate such a lens is based on diffractive optics, thus the thickness is much larger than the wavelength of light. While there has been great progress in the miniaturization of optical lenses by using metasurfaces, much attention has been paid to constructing a lens with a single focal point by using different geometry structures such as V-shape, [ 22,23,45,46 ] nanorods, [ 27,32,36 ] and nanoslits. [ 47 ] Although the work on metasurface lenses is in its infancy, it offers in the long run major opportunities if multifunction nanostructured lenses can be experimentally realized in ultrathin and fl at confi gurations. Here, we apply the concept of controllable interfacial phase discontinuity to realize an ultrathin fl at metasurface lens with multiple focal points along the longitudinal direction. Unlike the traditional multifoci diffractive lenses, the position and the polarization of the focal points can be controlled by changing the helicity of the incident light. Furthermore, the developed devices are ultrathin (40 nm) and planar, which can facilitate the system integration. Figure 1 shows the schematic of the plasmonic metasurface lens. It consists of nanorods with spatially varying orientation in three different regions marked by I, II, and III, as shown in Figure 1 a. The radius of region I (R-I) is r 1 , and the inner radius and outer radius of region II (R-II) are r 1 and r 2 . r 2 and r 3 are the inner radius and outer radius of region III (R-III). The relationship among r 1 , r 2 , and r 3 is governed by r r r : : 1: 2 : 3where r 1 = 40.0 µm, r 2 = 56.6 µm, and r 3 = 69.3 µm, which can ensure that the three regions R-I, R-II, and R-III have the same area. Therefore, the three parts of the metasurface will receive the same light energy fl ux when illuminated by a wellcollimated incident light beam.Metamaterials with artifi cially engineered subwavelength structures have been used to ...

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An ultrathin terahertz lens with axial long focal depth based on metasurfaces

Cited by 114 publications

References 29 publications

Microwave Tunable Metasurfaces Implemented With Ferroelectric Materials and Periodical Copper Wires

Microwave Tunable Metasurfaces Implemented With Ferroelectric Materials and Periodical Copper Wires

A Broadband Metasurface‐Based Terahertz Flat‐Lens Array

Longitudinal Multifoci Metalens for Circularly Polarized Light

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