A Thermal Tuning Meta-Duplex-Lens (MDL): Design and Characterization

Multifunctional metasurfaces play an important role in the development of integrated optical paths. However, some of the realizations of current multifunctional metasurface devices depend on polarization selectivity, and others change the polarization state of the outgoing light. Here, based on vanadium dioxide (VO2) phase change material, a strategy to design a meta-duplex-lens (MDL) is proposed and numerical simulation calculations demonstrate that at low temperature (about 300 K), VO2 behaves as a dielectric so that the MDL can act as a transmission lens (transmission efficiency of 87.6%). Conversely, when VO2 enters the metallic state (about 355 K), the MDL has the ability to reflect and polymerize electromagnetic waves and works as a reflection lens (reflection efficiency of 85.1%). The dielectric waveguide and gap-surface plasmon (GSP) theories are used in transmission and reflection directions, respectively. In order to satisfy the coverage of the phase gradient in the range of 2π in both cases, we set the antenna as a nanopillar with a high aspect ratio. It is notable that, via symmetrical antennas acting in concert with VO2 phase change material, the polarization states of both the incident light and the outgoing light are not changed. This reversible tuning will play a significant role in the fields of imaging, optical storage devices, communication, sensors, etc.

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Thermally switchable terahertz metasurface absorber composed of H-fractal and enabled by phase-change material of vanadium dioxide

Frequenz ◽

10.1515/freq-2021-0147 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Hassan Divdel ◽

Hamed Taghipour-Farshi ◽

Hassan Rasooli Saghai ◽

Mohammad-Ali Tavakoli Ghazi Jahani

Keyword(s):

Phase Transition ◽

Phase Change ◽

Phase Change Material ◽

Vanadium Dioxide ◽

Ground Plane ◽

Terahertz Range ◽

Metallic State ◽

Level 1 ◽

Change Material ◽

Level 2

Abstract A terahertz metasurface absorber with actively switchable bandwidth enabled by vanadium dioxide (VO2) is presented and investigated numerically. The VO2 is a phase-change material and its conductivity in the terahertz range changes by several orders of magnitude upon phase-transition. The metasurface consists of an H-shaped fractal resonator placed on top of a polyimide spacer and a ground-plane of gold. The resonator is composed of an H-shaped level-1 fractal of gold and VO2 strips that converts it to a level-2 fractal. At room temperatures, the VO2 is in the insulator state and the resonator reduces to a level-1 fractal offering narrowband absorption at 8.08 THz reaching 0.98 absorption. At higher temperatures, the VO2 is in the metallic state and the resonator is effectively a level-2 fractal with an absorption higher than 0.9 in a bandwidth of 6.63–9.89 THz.

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Influence of Phase Change Material Application on Photovoltaic Panel Performance

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.730.563 ◽

2017 ◽

Vol 730 ◽

pp. 563-568 ◽

Cited By ~ 4

Author(s):

Atthakorn Thongtha ◽

Hoy Yen Chan ◽

Paisit Luangjok

Keyword(s):

Experimental Design ◽

Phase Change ◽

Phase Change Material ◽

Incident Light ◽

Control Device ◽

Photovoltaic Module ◽

Photovoltaic Panel ◽

Electrical Efficiency ◽

Pv Module ◽

Change Material

This study investigated the application of phase change material and fins into photovoltaic panel. The experimental design was divided into 2 cases: conventional photovoltaic and photovoltaic with phase change material and fins. The thermal performance and electrical efficiency was tested under the solar radiation simulator between 500 and 1000 W/m2. The insolation intensity was tested by an incident-light photometer. The power of the nine halogen lamps was controlled by a simple voltage control device. It was found that temperature of normal PV module is constant after the tested time of 20 minutes. The temperatures of PV module with phase change material and fins were lower than a normal PV module throughout the testing duration. Approximately 2-6% of photovoltaic module temperatures have decreased and this have improved the electrical efficiency of about 1-4%. This indicated the use of phase change material and fins is able to decrease the photovoltaic module temperature and thus increase the efficiency of photovoltaic module cooling.

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Narrowband-to-broadband switchable and polarization-insensitive terahertz metasurface absorber enabled by phase-change material

Journal of Optics ◽

10.1088/2040-8986/ac3c50 ◽

2021 ◽

Author(s):

Seyed Hadi Badri ◽

M. M. Gilarlue ◽

Sanam SaeidNahaei ◽

Jong Su KIM

Keyword(s):

Phase Change ◽

Phase Change Material ◽

Ground Plane ◽

Metallic State ◽

Broadband Absorber ◽

Broadband Absorption ◽

Terahertz Absorber ◽

Wide Range ◽

Polarization Insensitive ◽

Change Material

Abstract A terahertz absorber with controllable and switchable bandwidth and insensitive to polarization is of great interest. Here, we propose and demonstrate a metasurface absorber with switchable bandwidth based on a phase-change material of vanadium dioxide (VO2) and verify its performance by the finite element method simulations. The metasurface absorber is composed of a hybrid cross fractal as a resonator separated from a gold ground-plane by a polyimide spacer. Switching from narrowband to broadband absorber is achieved via connecting VO2 patches to the gold first-order cross fractal converting the resonator to a third-order cross fractal. In the insulator phase of VO2, the main narrowband absorption occurs at the frequency of 6.05 THz with a 0.99 absorption and a full-width half-maximum (FWHM) of 0.35 THz. Upon insulator-to-metal transition of VO2, the metasurface achieves a broadband absorption with the FWHM of 6.17 THz. The simulations indicate that by controlling the partial phase-transition of VO2, we can tune the bandwidth and absorption level of the absorber. Moreover, the designed absorber is insensitive to polarization due to symmetry and works well for a very wide range of incident angles. In the metallic state of VO2, the absorber has an absorption exceeding 0.5 in the 3.57-8.45 THz frequency range with incident angles up to 65°.

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Thermal Frequency Reconfigurable Electromagnetic Absorber Using Phase Change Material

Sensors ◽

10.3390/s18103506 ◽

2018 ◽

Vol 18 (10) ◽

pp. 3506 ◽

Cited By ~ 10

Author(s):

Heijun Jeong ◽

Jeong-Heum Park ◽

You-Hwan Moon ◽

Chang-Wook Baek ◽

Sungjoon Lim

Keyword(s):

Phase Change ◽

Phase Change Material ◽

Electromagnetic Waves ◽

Amorphous State ◽

Normal Incidence ◽

Electromagnetic Properties ◽

Resistive State ◽

Absorption Frequency ◽

Frequency Changes ◽

Change Material

In this study, we propose a thermal frequency reconfigurable electromagnetic absorber using germanium telluride (GeTe) phase change material. Thermally-induced phase transition of GeTe from an amorphous high-resistive state to a crystalline low-resistive state by heating is used to change the resonant frequency of the absorber. For full-wave simulation, the electromagnetic properties of GeTe at 25 °C and 250 °C are characterized at 10 GHz under normal incidence for electromagnetic waves. The proposed absorber is designed based on the characterized electromagnetic parameters of GeTe. A circular unit cell is designed and GeTe is placed at a gap in the circle to maximize the switching range. The performance of the proposed electromagnetic absorber is numerically and experimentally demonstrated. Measurement results indicate that the absorption frequency changes from 10.23 GHz to 9.6 GHz when the GeTe film is altered from an amorphous state at room temperature to a crystalline state by heating the sample to 250 °C. The absorptivity in these states is determined to be 91% and 92%, respectively.

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