Switchable bifunctional metasurface based on VO2 for ultra-broadband polarization conversion and perfect absorption in same infrared waveband

Strontium titanate (STO), the dielectric material, has caught the world’s attention due to its outstanding properties, such as high permittivity, high refractive index, and low loss in the terahertz band. Its permittivity is relevant to the environment temperature. Herein, a multifunctional meta-surface composed of a dielectric-metal hybrid antenna array has been demonstrated, which is a single-layer STO elliptic cylinder. On the one hand, when the environment temperature is 300 K, the proposed meta-surface can achieve perfect absorption and polarization conversion in the frequency range from 0.1 to 0.25 THz; particularly, the meta-surface absorptance can reach 99.97% and 99.92% at a frequency of 0.103 and 0.13 THz respectively, and while it is used as a polarization conversion device, the degree of circular polarization and the ellipticity angle can reach 0.986 and 44.5° at a frequency of 0.228 THz. On the other hand, when the environment temperature changes from 300 to 450 K, the absorption peak changes with the temperature, and the average absorptance reaches 96% at resonance frequency. The proposed meta-surface can be applied in many fields, such as optical sensing, imaging, and energy harvesting. Moreover, it provides a potential solution to research the integrated device in a complex electromagnetic environment.

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Reconfigurable Continuous Meta-Grating for Broadband Polarization Conversion and Perfect Absorption

Materials ◽

10.3390/ma14092212 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2212

Author(s):

Yijia Huang ◽

Tianxiao Xiao ◽

Zhengwei Xie ◽

Jie Zheng ◽

Yarong Su ◽

...

Keyword(s):

Amorphous State ◽

Functional Materials ◽

Building Blocks ◽

Infrared Region ◽

Superior Performance ◽

Polarization Conversion ◽

Perfect Absorption ◽

Dual Functional ◽

Thermal Emissivity ◽

Unit Cells

As promising building blocks for functional materials and devices, metasurfaces have gained widespread attention in recent years due to their unique electromagnetic (EM) properties, as well as subwavelength footprints. However, current designs based on discrete unit cells often suffer from low working efficiencies, narrow operation bandwidths, and fixed EM functionalities. Here, by employing the superior performance of a continuous metasurface, combined with the reconfigurable properties of a phase change material (PCM), a dual-functional meta-grating is proposed in the infrared region, which can achieve a broadband polarization conversion of over 90% when the PCM is in an amorphous state, and a perfect EM absorption larger than 91% when the PCM changes to a crystalline state. Moreover, by arranging the meta-grating to form a quasi-continuous metasurface, subsequent simulations indicated that the designed device exhibited an ultralow specular reflectivity below 10% and a tunable thermal emissivity from 14.5% to 91%. It is believed that the proposed devices with reconfigurable EM responses have great potential in the field of emissivity control and infrared camouflage.

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Broadband polarization conversion metasurface for RCS reduction

12th European Conference on Antennas and Propagation (EuCAP 2018) ◽

10.1049/cp.2018.1176 ◽

2018 ◽

Author(s):

F. Samadi ◽

M. Akbari ◽

R. Chaharmir ◽

A.R. Sebak

Keyword(s):

Polarization Conversion

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Simple design of efficient broadband multifunctional polarization converter for X-band applications

Scientific Reports ◽

10.1038/s41598-021-81586-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Thi Kim Thu Nguyen ◽

Thi Minh Nguyen ◽

Hong Quang Nguyen ◽

Thanh Nghia Cao ◽

Dac Tuyen Le ◽

...

Keyword(s):

Circular Polarization ◽

Incident Angle ◽

Polarization Conversion ◽

Simple Design ◽

Cross Polarization ◽

Polarization Converter ◽

Frequency Bands ◽

X Band ◽

Cost Efficient ◽

Patch Resonators

AbstractA simple design of a broadband multifunctional polarization converter using an anisotropic metasurface for X-band application is proposed. The proposed polarization converter consists of a periodic array of the two-corner-cut square patch resonators based on the FR-4 substrate that achieves both cross-polarization and linear-to-circular polarization conversions. The simulated results show that the polarization converter displays the linear cross-polarization conversion in the frequency range from 8 to 12 GHz with the polarization conversion efficiency above 90%. The efficiency is kept higher than 80% with wide incident angle up to 45°. Moreover, the proposed design achieves the linear-to-circular polarization conversion at two frequency bands of 7.42–7.6 GHz and 13–13.56 GHz. A prototype of the proposed polarization converter is fabricated and measured, showing a good agreement between the measured and simulated results. The proposed polarization converter exhibits excellent performances such as simple structure, multifunctional property, and large cost-efficient bandwidth and wide incident angle insensitivity in the linear cross polarization conversion, which can be useful for X-band applications. Furthermore, this structure can be extended to design broadband polarization converters in other frequency bands.

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Dual-Band RCS Reduction of a Fabry-Perot Antenna Based on Polarization Conversion Metasurface

2020 Cross Strait Radio Science & Wireless Technology Conference (CSRSWTC) ◽

10.1109/csrswtc50769.2020.9372733 ◽

2020 ◽

Author(s):

Hongwei Chen ◽

Qunsheng Cao ◽

Jinwei Liang

Keyword(s):

Dual Band ◽

Polarization Conversion ◽

Fabry Perot

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Plasmonic hot-electron photodetection with quasi-bound states in the continuum and guided resonances

Nanophotonics ◽

10.1515/nanoph-2021-0069 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Wenhao Wang ◽

Lucas V. Besteiro ◽

Peng Yu ◽

Feng Lin ◽

Alexander O. Govorov ◽

...

Keyword(s):

Bound States ◽

Structural Parameters ◽

Hybrid Structure ◽

Fine Tuning ◽

Hot Electrons ◽

Hot Electron ◽

Perfect Absorption ◽

High Loss ◽

Guided Mode ◽

The Continuum

Abstract Hot electrons generated in metallic nanostructures have shown promising perspectives for photodetection. This has prompted efforts to enhance the absorption of photons by metals. However, most strategies require fine-tuning of the geometric parameters to achieve perfect absorption, accompanied by the demanding fabrications. Here, we theoretically propose a Ag grating/TiO2 cladding hybrid structure for hot electron photodetection (HEPD) by combining quasi-bound states in the continuum (BIC) and plasmonic hot electrons. Enabled by quasi-BIC, perfect absorption can be readily achieved and it is robust against the change of several structural parameters due to the topological nature of BIC. Also, we show that the guided mode can be folded into the light cone by introducing a disturbance to become a guided resonance, which then gives rise to a narrow-band HEPD that is difficult to be achieved in the high loss gold plasmonics. Combining the quasi-BIC and the guided resonance, we also realize a multiband HEPD with near-perfect absorption. Our work suggests new routes to enhance the light-harvesting in plasmonic nanosystems.

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