Ultra-broadband linear polarization converter based on anisotropic metasurface

Xu, Jia; Li, Rongqiang; Wang, Shenyun; Han, Tong

doi:10.1364/oe.26.026235

Cited by 127 publications

(42 citation statements)

References 28 publications

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“…Such structures can be engineered to act as artificial impedance surfaces that produce a controlled reflection response to an incident wave. Controlling the reflection phase of the incident wave is essential in many radio frequency, microwave and THz applications, including: propagating mode to surface mode conversion 4 , anomalous reflection 5 , reflectarray antennas [6][7][8][9][10][11][12] , absorbers [13][14][15] , high impedance surface based antennas 16 , transmitarrays [17][18][19] and anisotropic polarization converters 20 .…”

Section: Ultra-low-loss Tunable Piezoelectric-actuated Metasurfaces Amentioning

confidence: 99%

Ultra-low-loss tunable piezoelectric-actuated metasurfaces achieving 360° or 180° dynamic phase shift at millimeter-waves

Vassos

Churm

Feresidis

2020

Sci Rep

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Phase shifting metasurfaces typically consist of an ordered metallic geometry that is patterned onto a dielectric substrate and incorporate active devices or materials that enable dynamic tuning. Existing methods at mm-wave and submillimeter bands typically suffer from high losses, which are predominantly produced by the inherent limitations of the tuning elements or materials. This report presents a new, ultra-low-loss and phase-tunable, reflection type metasurface design, which outperforms previously reported technologies in terms of phase shifting and loss. The proposed technique utilizes a variable air cavity, formed between a periodic array and a ground plane, which is controlled by means of a piezoelectric actuator. Two metasurface designs are presented and experimentally tested. Firstly, a square patch element metasurface that is capable of achieving a continuous 180° phase shift across a wide bandwidth, between 35 and 65 GHz. Also presented is a double-cross element metasurface that provides full 360° phase control between 57 and 62 GHz. The variable air cavity is controlled by means of a piezoelectric actuator that supports and varies the height of a ground plane, providing highly accurate, millisecond, displacement. Unlike conventional tuning methods, the tuning mechanism, in this case the moving ground plane, introduces no additional sources of loss and enables an average loss performance of 1 dB. Full-wave simulations are presented and experimentally validated with measurements of both metasurface prototypes. The proposed approach is scalable from microwave up to THz frequencies, due to the electro-mechanical and low loss nature of the tuning.

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Section: Ultra-low-loss Tunable Piezoelectric-actuated Metasurfaces Amentioning

confidence: 99%

Ultra-low-loss tunable piezoelectric-actuated metasurfaces achieving 360° or 180° dynamic phase shift at millimeter-waves

Vassos

Churm

Feresidis

2020

Sci Rep

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“…Metamaterials are novel artificial structures that are designed for specified functions like negative refractive index [1][2][3], polarization conversion [4][5][6] and perfect absorption [7][8][9]. Metasurfaces possess the advantages of small losses and are easy to manufacture [10,11], and have been attractive in recent years.…”

Section: Introductionmentioning

confidence: 99%

Polarization Controlled Dual Functional Reflective Planar Metalens in Near Infrared Regime

et al. 2020

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The metalens has been a hotspot in scientific communications in recent years. The polarization-controlled functional metalens is appealing in metalens investigation. We propose a metalens with dual functions that are controlled by polarization states. In the first design, when applied with x-and y-polarized light, two focal spots with different focal lengths are acquired, respectively. The proposed metalens performs well when illuminated with adjacent wavelengths. In the second design, the reflected light is focused when applied with x-polarized light, and when applied with y-polarized light, the reflected light is split into two oblique paths. We believe that the results will provide a new method in light manipulation.

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“…Polarization conversion is a common practice in many optical elements present in, for example, displays, antennas and beam splitters. [1][2][3][4][5][6][7] A polarization converter that is often used is a wave plate; a birefringent element that converts a polarization state by inducing a phase shift between orthogonal electric-field left-handed CP light transmitted by the first polarizer to righthanded CP light, which is then reflected by the second polarizer, increasing the overall reflectivity of the optical device to 100%.…”

Section: Introductionmentioning

confidence: 99%

Temperature‐Responsive Polymer Wave Plates as Tunable Polarization Converters

Kragt

Gessel

Schenning

et al. 2019

Advanced Optical Materials

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components of electro-magnetic waves. The simplest wave plates have a homogeneous uniaxial birefringence (Δn) with a thickness (d) and induce a phase shift between the two orthogonal waves according toin which λ is the wavelength and k the induced phase shift divided by 2π. [1,8,9] Liquid crystals (LCs) are frequently used as wave plate materials. By programming the Δn and d of a uniaxial aligned LC quarter-and half-wave plates can be easily fabricated. Also achromatic polarization converters can be obtained by stacking multiple wave plates using the principle of retardation compensation or using configurations involving twisted nematic LCs. [1,[8][9][10][11][12][13][14][15][16][17][18] Wave plates based on nonpolymerized LCs in cells can also be switched using electric fields, which among others resulted in the billion dollar LC display industry. [1,19,20] To widen its application range it would be appealing to make wave plate films that are responsive to other stimuli such as temperature. However, stimuli-responsive polymer wave plates have never been reported so far.We recently reported on a reflective LC coating based on a semi-interpenetrating polymer network (semi-IPN) composed of a LC elastomer (LCE) and a helical LC network (LCN). The coating showed a fast and reversible decrease in reflection band intensity with increasing temperature, which could be tuned by the polymer network density. [21] In this work, we developed temperature-responsive polymer wave plates, which reversibly change from a full-wave to a half-wave plate upon heating. The wave plate consists of a uniaxial aligned nematic semi-IPN in which a non-crosslinked LCE interpenetrates through an LCN. Upon heating above the nematic-to-isotropic transition temperature (T N-I ) of the semi-IPN, the LCE loses order and the effective Δn of the material halves, while d remains constant, thereby changing the polymer film from a full-wave to a half-wave plate. We demonstrate its function by sandwiching the temperatureresponsive wave plate between two identical cholesteric LC (CLC) polarizers reflecting right-handed circular polarized (CP) light around the λ for which the wave plate is operative (Figure 1). Below the T N-I , the left-handed CP light transmitted by the first polarizer is effectively not affected by the full-wave plate and thus also transmitted by the second polarizer, resulting in an overall reflectivity of 50%. Upon heating above T N-I , the wave plate turns into a half-wave plate, which converts the A temperature-responsive polarization converter, which reversibly changes from a full-wave to a half-wave plate upon heating, is developed. The polymer wave plate has a controlled thickness and is based on a uniaxial aligned nematic semi-interpenetrating network coating containing a specific concentration of a non-crosslinked liquid crystal elastomer. Upon heating, the effective birefringence of the wave plate halves without changing the thickness. The function of the wave plate is demonstrated by sandwiching the tunable polarization conver...

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Ultra-broadband linear polarization converter based on anisotropic metasurface

Cited by 127 publications

References 28 publications

Ultra-low-loss tunable piezoelectric-actuated metasurfaces achieving 360° or 180° dynamic phase shift at millimeter-waves

Ultra-low-loss tunable piezoelectric-actuated metasurfaces achieving 360° or 180° dynamic phase shift at millimeter-waves

Polarization Controlled Dual Functional Reflective Planar Metalens in Near Infrared Regime

Temperature‐Responsive Polymer Wave Plates as Tunable Polarization Converters

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