We report a programmable phase change medium-based hyperbolic metamaterial (HMM) with emphasis on the optical response characterized by adjusting the electrical constants and/or structural parameters (such as thicknesses and/or filling fraction) of the constituent materials. The investigation reveals broad area of the type I HMM in the visible regime for the device comprising silver and stibnite mediums. The angle- and polarization-insensitive properties of the configuration demonstrate an in-band rejection of over −75 dB, tunable in the range of 0.5723 to 0.639 μm, and an 8-bit encoding bandwidth of 12 nm. Also, the study yields two distinct modulation mechanisms at the incidence angle of 62 deg, viz. a Brewster modulator in the UV regime (which solely depends on the incidence obliquity) and an angle-insensitive reflection modulator in the visible regime—the features that are programmable according to the thermal ambience.
In the field of science, there is a significant interest in graphene due to its extraordinary properties such as high electrical
conductivity, good electrochemical stability and excellent mechanical behavior. This paper presents the direct graphene
growth on interdigital electrodes by plasma enhanced chemical vapor deposition (PECVD) using Ni catalyst and
methane (CH4) as the carbon source. The 100 nm of Ni was deposited on the top of SiO2 substrate functional as catalyst
and electrode of MEMS supercapacitor. The growth of graphene was investigated at temperature 1000°C at 10 minutes
and at fix power of 40 Watt. The morphology and structure of as- grown graphene were characterized by Raman
spectroscopy, Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM). From
Raman spectra, it is observed that the intensity ratio of the 2D band to G band produced a good quality bilayer graphene.
The absorption characteristics of complex medium structures having metasurfaces comprised of columnar nanorods of gold were investigated. In this stream, a periodically arranged assembly of vertical gold nanorods of circular and elliptical cross sections, backed by chromium nanorods of the same cross-sectional size and shape, was considered to be the metasurface, and the comparative features of the absorption characteristics were emphasized. The results exhibit very high absorption corresponding to certain wavelengths in the visible span, and the absorber having elliptical gold nanorods yields a better performance than the one with circular nanorods in terms of the magnitude/smoothness of the absorption peaks.
Metamaterials have been of great interest owing to multifarious technological applications. Among various applications of scientific need, the perfect absorber kind of property of metamaterials remains prudent. Within the context, this investigation describes the filtering/absorber applications of metasurfaces comprised of columnar nanorods of gold having circular and elliptical cross-sections. The spectral features of such absorbers are investigated in terms of absorptivity in the visible to infrared (IR) regimes. The results indicate of almost perfect absorption corresponding to certain wavelengths in the IR span. Also, multiple absorption peaks would determine the filtering characteristics of the structures under consideration. It has been found that the absorber having circular nanorods exhibits better performance than the one with elliptical nanorods in terms of the magnitude/smoothness of absorption peaks in the entire electromagnetic spectral region of interest; the case of elliptical nanorods makes the absorption spectra to yield too much of flickers in the IR range of wavelength.
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