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Peng X.-Y.,Institute of Materials Research and Engineering of Singapore | Wang B.,Institute of Materials Research and Engineering of Singapore | Teng J.,Institute of Materials Research and Engineering of Singapore | Kana Kana J.B.,Nanoscience and Nanotechnology Laboratories | Zhang X.,Institute of Materials Research and Engineering of Singapore
Journal of Applied Physics | Year: 2013

We demonstrate via the numerical simulation the modulation of the transmission of visible and near-infrared light through a hybrid grating structure containing a gold metallic wire-grid grating patterned on a thermochromic vanadium dioxide (VO2) thin film. We find that the transmission through the subwavelength slits of this hybrid device is significantly modulated in the near-infrared region due to the phase transition of VO2 film from insulator to metal when the temperature increases from 30 °C to 85 °C. By optimizing the hybrid-grating architecture parameters, the best switching efficiency of our hybrid grating at 1.5 μm reaches to 40%, and extinction ratio is larger than 1013. The capability of switching on/off and fine tuning of the thick hybrid grating parameters make our hybrid-grating structure a promising candidate of an active broadband linear polarizer with high switching efficiency and extinction ratio. © 2013 AIP Publishing LLC. Source


Liu Y.,Changchun University of Science and Technology | Liu Y.,CAS Chongqing Institute of Green and Intelligent Technology | Dong J.-M.,Changchun University of Science and Technology | Dong J.-M.,CAS Chongqing Institute of Green and Intelligent Technology | And 3 more authors.
5th International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale, 3M-NANO 2015 - Conference Proceedings | Year: 2015

The biggest challenge of the practical applications of metamaterial-based perfect absorbers remains on the architectural design structure to engineer a system capable to achieve a near unity absorption, large absorption bandwidth and tunable resonance frequency and absorption strength. We propose and demonstrate an active visible and near-infrared metamaterial absorber formed by a sandwich of gold square metallic patch-vanadium dioxide thin film-gold layer. It shows a high absorptance up to 86% at the external temperature stimuli of 30°C, and about 30% at 85°C in the wide wavelength range from 0.9 μm to 1.5 μm. The proposed absorber has potential applications in active thermal control of electronic, optical and thermal devices. © 2015 IEEE. Source


Kana Kana J.B.,Nanoscience and Nanotechnology Laboratories | Kana Kana J.B.,University of the Western Cape | Kana Kana J.B.,University of Yaounde I | Kana Kana J.B.,African Laser Center | And 11 more authors.
Optical Materials | Year: 2010

Vanadium dioxide (VO2) thin films were deposited onto Corning glass substrates by rf reactive inverted cylindrical magnetron sputtering at different substrate temperatures (Ts) ranging from 450 to 600 °C. The influence of substrate temperature on the structural and optical properties was systematically investigated. It revealed that the crystallinity of the VO2 films improved significantly with Ts. The substrate temperature to obtain films with transition temperature (Tc ∼ 70 °C) similar to VO2 bulk single crystal was 450-500 °C, while high substrate temperatures from 550 to 600 °C tend to shift Tc towards higher temperatures from 75 to 80 °C keeping the sharpness of the transition unaltered. Even if the variation of the Tc of VO2 is not dramatic "variation from 70 to 80 °C" with increasing Ts is substantial for undoped VO2 thin films. This sizeable variation of ∼10 °C confirms the tunability of the Tc of VO2 through Ts. © 2010 Elsevier B.V. All rights reserved. Source


Kana Kana J.B.,Nanoscience and Nanotechnology Laboratories | Kana Kana J.B.,A+ Network | Kana Kana J.B.,University of Yaounde I | Ndjaka J.M.,University of Yaounde I | And 4 more authors.
Optics Communications | Year: 2011

Smart materials with reversible tunable optical constants from visible to near-infrared wavelengths could enable excellent control over the resonant response in metamaterials, tunable plasmonic nanostructures, optical memory based on phase transition and thermally tunable optical devices. Vanadium dioxide (VO2) is a promising candidate that exhibits a dramatic change in its complex refraction index or complex dielectric function arising from a structural phase transition from semiconductor to metal at a critical temperature of 70 °C. We demonstrated the thermal controllable reversible tunability of optical constants of VO2 thin films. The optical/dielectric constants showed an abrupt thermal hysteresis which confirms clearly the electronic structural changes. Temperature dependence of dielectric constants as well as optical conductivity of sputtered VO2 thin films was also reported and compared to previous theoretical and experimental reports. © 2010 Elsevier B.V. All rights reserved. Source

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