IEEE Access (Jan 2020)
A Wide Incident Angle, Ultrathin, Polarization-Insensitive Metamaterial Absorber for Optical Wavelength Applications
Abstract
Polarization-insensitive metamaterial absorbers (MMAs) are currently attracting a great deal of interest throughout the optical region. These kinds of MMAs can be used as energy harvesting, thermal imaging, plasmonic sensor, magnetic imaging, light trapping, optical modulator, and can help to decipher an inherence for the field. Here, a polarization-insensitive ultrathin MMA has been proposed with an extensive incident angular stability for the optical region with a sandwiched three-layer structure. Tungsten (W) and silicon dioxide (SiO2) have been chosen as materials for their various advantages in the optical spectrum with higher temperature stability. The design simulated with the finite integration technique (FIT), and validation of the simulated data is assured with the interference theory model (ITM). Underlying physics of the absorption characteristics and performance of the structure are immensely explained. The design acquired an average absorption of 96.7% from 380nm to 700nm and 96.61% for both transverse electric (TE) and transverse magnetic (TM) polarization. It has a peak absorption of 99.99% at 498.25nm, and over 99% from 460nm to 540nm, due to a very good impedance match with plasmonic resonance characteristics. For both TE and TM mode, it has wide angular independence up to 60°, which can be used for solar cell and solar thermo-photovoltaics (STPV). The various parametric sweep also analyzed for acquiring the geometric shape with a wide bandwidth to find resonance wavelength. As the MMA shifts its resonance wavelength with the change of its dielectric thickness, it can be used as an optical sensor. Changing dielectric in a Pyrex will enable the structure to be used as a light detector. Such outstanding absorption properties render the proposed MMA a successful candidate for the optical wavelength applications mentioned above.
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