Research

12 pages, 7676 KiB

Open AccessArticle

Transmission Enhancement through Sub-Wavelength Aperture Based on Regulable Water-Based Metamaterial

by Pengfei Shi, Xiaodong Li, Hongge Zhao, Youfu Tang, Jingwei Zhu, Renjing Gao and Shutian Liu

Photonics 2023, 10(2), 181; https://doi.org/10.3390/photonics10020181 - 08 Feb 2023

Viewed by 962

Abstract

A realization form of the Mie resonance with adjustable characteristics based on a water-based metamaterial is proposed. A novel local electromagnetic field coupling mechanism based on a water-based metamaterial is established, which is used for transmission enhancement through the sub-wavelength aperture for the [...] Read more.

A realization form of the Mie resonance with adjustable characteristics based on a water-based metamaterial is proposed. A novel local electromagnetic field coupling mechanism based on a water-based metamaterial is established, which is used for transmission enhancement through the sub-wavelength aperture for the first time. The water-based metamaterial particle for transmission enhancement at a specific frequency is designed. By designing the microfluidic control system to control the water filling (i.e., height) of the metamaterial particle, the adjustable transmission enhancement characteristics are realized. The influence of bilateral symmetry and flexible deformation of the metamaterial particle on the transmission characteristics is analyzed. The influence of the design parameters on the enhanced transmission characteristics is discussed. Full article

(This article belongs to the Special Issue Active/Reconfigurable Metasurfaces)

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10 pages, 10075 KiB

Open AccessCommunication

Design of the Polarization-Independent Wavelength Multiplexing Holographic Metasurface

by Tianyu Zhao, Yihui Wu, Yi Xing, Yue Wang, Jie Wu and Wenchao Zhou

Photonics 2023, 10(2), 139; https://doi.org/10.3390/photonics10020139 - 30 Jan 2023

Cited by 1 | Viewed by 1693

Abstract

Metasurface regulates the polarization, phase, amplitude, frequency, and other characteristics of electromagnetic waves through the subwavelength microstructure. By using its polarization characteristics, it can realize the functions of optical rotation and vector beam generation. It is the most widely used method of regulation. [...] Read more.

Metasurface regulates the polarization, phase, amplitude, frequency, and other characteristics of electromagnetic waves through the subwavelength microstructure. By using its polarization characteristics, it can realize the functions of optical rotation and vector beam generation. It is the most widely used method of regulation. However, parallel optical manipulation, imaging, and communication usually require polarization-insensitive focused (or vortex) arrays of beams, so polarization-independent wavelength multiplexing optical systems need to be considered. In this paper, the genetic algorithm combined with the computer-generated hologram (CGH) is used to control the transmission phase of the structure itself, and on the basis of wavelength multiplexing, the corresponding array of focused or vortex beams without the polarization selection property is realized. The simulation software results show that the method has a huge application prospect in optical communication and optical manipulation. Full article

(This article belongs to the Special Issue Active/Reconfigurable Metasurfaces)

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12 pages, 2941 KiB

Open AccessArticle

Non-Mechanical Multiplexed Beam-Steering Elements Based on Double-Sided Liquid Crystal Metasurfaces

by Maxim V. Gorkunov, Artur R. Geivandov, Alena V. Mamonova, Ivan V. Simdyankin, Irina V. Kasyanova, Alexander A. Ezhov and Vladimir V. Artemov

Photonics 2022, 9(12), 986; https://doi.org/10.3390/photonics9120986 - 15 Dec 2022

Cited by 1 | Viewed by 1469

Abstract

We propose, optimize, fabricate and test beam-steering elements based on double-sided liquid-crystal (LC) metasurfaces allowing for diffractive and spectral multiplexing, and thus covering three different beam deflection directions each. While straightforward parallel design requires one diffractive beam-steering element per a direction determined by [...] Read more.

We propose, optimize, fabricate and test beam-steering elements based on double-sided liquid-crystal (LC) metasurfaces allowing for diffractive and spectral multiplexing, and thus covering three different beam deflection directions each. While straightforward parallel design requires one diffractive beam-steering element per a direction determined by Bragg’s law, double-sided LC-metasurfaces are remarkably flexible and allow optimization for three operation modes at different applied voltages: zero-voltage mode with dominant +1 order red light and +2 order blue light diffraction; intermediate mode at 1.4–1.6 V voltage with dominant +1 order blue light diffraction; and transparent mode at 5 V voltage. We comprehensively study three such elements with 6, 8 and 10 micrometer periods and verify their capability of deflecting blue and red light beams with 40–70% efficiencies in nine target directions with 10 ms characteristic switching times. Full article

(This article belongs to the Special Issue Active/Reconfigurable Metasurfaces)

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13 pages, 4045 KiB

Open AccessArticle

Reflective Terahertz Metasurfaces Based on Non-Volatile Phase Change Material for Switchable Manipulation

by Natsima Sakda, Ratchapak Chitaree and B. M. Azizur Rahman

Photonics 2022, 9(8), 508; https://doi.org/10.3390/photonics9080508 - 22 Jul 2022

Cited by 3 | Viewed by 1978

Abstract

Recently, metasurfaces have been investigated and exploited for various applications in the THz regime, including modulators and detectors. However, the responsive properties of the metasurface in THz stay fixed once the fabrication process is complete. This limitation can be modified when integrating the [...] Read more.

Recently, metasurfaces have been investigated and exploited for various applications in the THz regime, including modulators and detectors. However, the responsive properties of the metasurface in THz stay fixed once the fabrication process is complete. This limitation can be modified when integrating the phase change material (PCM), whose states are switchable between crystalline and amorphous, into the metasurface structure. This characteristic of the PCM is appealing in achieving dynamic and customizable functionality. In this work, the reflective metasurface structure is designed as a hexagonal unit deposited on a polyimide substrate. The non-volatile PCM chosen for the numerical study is germanium antimony tellurium (GST). Our proposed phase change metasurface provides two resonant frequencies located at 1.72 and 2.70 THz, respectively; one of them shows a high contrast of reflectivity at almost 80%. The effects of geometrical parameters, incident angles, and polarization modes on the properties of the proposed structure are explored. Finally, the performances of the structure are evaluated in terms of the insertion loss and extinction ratio. Full article

(This article belongs to the Special Issue Active/Reconfigurable Metasurfaces)

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9 pages, 1559 KiB

Open AccessArticle

Research of Gate-Tunable Phase Modulation Metasurfaces Based on Epsilon-Near-Zero Property of Indium-Tin-Oxide

by Xin Li, Qiufan Cheng, Shiliang Guo and Zhiquan Li

Photonics 2022, 9(5), 323; https://doi.org/10.3390/photonics9050323 - 09 May 2022

Cited by 1 | Viewed by 2103

Abstract

In this paper, we proposed a reflection phase electrically tunable metasurface composed of an Au/Al₂O₃/ITO/Au grating structure. This antenna array can achieve a broad phase shift continuously and smoothly from 0° to 320° with a 5.85 V applied voltage [...] Read more.

In this paper, we proposed a reflection phase electrically tunable metasurface composed of an Au/Al₂O₃/ITO/Au grating structure. This antenna array can achieve a broad phase shift continuously and smoothly from 0° to 320° with a 5.85 V applied voltage bias. Tunability arises from field-effect modulation of the carrier concentrations or accumulation layer at the Al₂O₃/ITO interface, which excites electric and magnetic resonances in the epsilon-near-zero region. To make the reflected phase tuning range as wide as possible, some of the intensity of the reflected light is lost due to the excited surface plasmon effect. Simulation results show that the effect of optimal phase modulation can be realized at a wavelength range of 1550 nm by modulating the carrier concentration in our work. Additionally, we utilized an identical 13-unit array metasurface to demonstrate its application to the beam steering function. This active optical metasurface can enable a new realm of applications in ultrathin integrated photonic circuits. Full article

(This article belongs to the Special Issue Active/Reconfigurable Metasurfaces)

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7 pages, 1355 KiB

Open AccessCommunication

All-Dielectric Metasurface Based on Complementary Split-Ring Resonators for Refractive Index Sensing

by Mohsen Samadi, Fatemeh Abshari, José F. Algorri, Pablo Roldán-Varona, Luis Rodríguez-Cobo, José M. López-Higuera, José M. Sánchez-Pena, Dimitrios C. Zografopoulos and Francesco Dell’Olio

Photonics 2022, 9(3), 130; https://doi.org/10.3390/photonics9030130 - 25 Feb 2022

Cited by 13 | Viewed by 3100

Abstract

Thanks to their lower losses and sharper resonances compared to their metallic counterparts, all-dielectric metasurfaces are attracting a quickly growing research interest. The application of such metasurfaces in the field of refractive index sensing is extremely attractive, especially due to the expected high [...] Read more.

Thanks to their lower losses and sharper resonances compared to their metallic counterparts, all-dielectric metasurfaces are attracting a quickly growing research interest. The application of such metasurfaces in the field of refractive index sensing is extremely attractive, especially due to the expected high performance and the simplicity of the sensing element excitation and readout. Herein, we report on an all-dielectric silicon metasurface based on complementary split-ring resonators (CSRRs) optimized for refractive index sensing. A quasi-bound state in the continuum (quasi-BIC) with an ultra-high quality factor can be excited in the near-infrared (NIR) window by violating the structure symmetry. By using the three-dimensional finite element method (3D-FEM), a refractive index sensor for biomedical applications with an ultra-high figure of merit (FoM > 100,000 RIU⁻¹) has been designed, exploiting the quasi-BIC resonance. The proposed design strategy opens new avenues for developing flat biochemical sensors that are accurate and responsive in real time. Full article

(This article belongs to the Special Issue Active/Reconfigurable Metasurfaces)

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8 pages, 5246 KiB

Open AccessCommunication

LIDAR and Beam Steering Tailored by Neuromorphic Metasurfaces Dipped in a Tunable Surrounding Medium

by Giuseppe Emanuele Lio and Antonio Ferraro

Photonics 2021, 8(3), 65; https://doi.org/10.3390/photonics8030065 - 26 Feb 2021

Cited by 23 | Viewed by 4330

Abstract

The control of amplitude, losses and deflection of light with elements of an optical array is of paramount importance for realizing dynamic beam steering for light detection and ranging applications (LIDAR). In this paper, we propose an optical beam steering device, operating at [...] Read more.

The control of amplitude, losses and deflection of light with elements of an optical array is of paramount importance for realizing dynamic beam steering for light detection and ranging applications (LIDAR). In this paper, we propose an optical beam steering device, operating at a wavelength of 1550 nm, based on high index material as molybdenum disulfide (

M o S_{2}

) where the direction of the light is actively controlled by means of liquid crystal. The metasurface have been designed by a deep machine learning algorithm jointed with an optimizer in order to obtain univocal optical responses. The achieved numerical results represent a promising way for the realization of novel LIDAR for future applications with increase control and precision. Full article

(This article belongs to the Special Issue Active/Reconfigurable Metasurfaces)

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10 pages, 1614 KiB

Open AccessCommunication

Switchable Metasurface with VO₂ Thin Film at Visible Light by Changing Temperature

by Jin-Kyu Yang and Hyeon-Seok Jeong

Photonics 2021, 8(2), 57; https://doi.org/10.3390/photonics8020057 - 18 Feb 2021

Cited by 16 | Viewed by 3915

Abstract

We numerically demonstrated switchable metasurfaces using a phase change material, VO

_{2}

by temperature change. The Pancharatnam–Berry metasurface was realized by using an array of Au nanorods on top of a thin VO

_{2}

film above an Au film, where the optical property [...] Read more.

We numerically demonstrated switchable metasurfaces using a phase change material, VO

_{2}

by temperature change. The Pancharatnam–Berry metasurface was realized by using an array of Au nanorods on top of a thin VO

_{2}

film above an Au film, where the optical property of the VO

_{2}

film is switched from the insulator phase at low temperature to the metal phase at high temperature. At the optimal structure, polarization conversion efficiency of the normal incident light is about 75% at low temperature while that is less than 0.5% at high temperature in the visible region (

λ \sim

700 nm). Various functionalities of switchable metasurfaces were demonstrated such as polarization conversion, beam steering, Fourier hologram, and Fresnel hologram. The thin-VO

_{2}

-film-based switchable metasurface can be a good candidate for various switchable metasurface devices, for example, temperature dependent optical sensors, beamforming antennas, and display. Full article

(This article belongs to the Special Issue Active/Reconfigurable Metasurfaces)

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