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Title: Perfect terahertz absorber using fishnet based metafilm

Abstract

We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unitymore » at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
979674
Report Number(s):
LA-UR-09-07901; LA-UR-09-7901
TRN: US201011%%371
DOE Contract Number:
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: Conference on Lasers and Electro Optics ; May 16, 2010 ; San Jose, CA
Country of Publication:
United States
Language:
English
Subject:
42; ABSORPTION; ABSORPTIVITY; COMPOSITE MATERIALS; DESIGN; DIELECTRIC MATERIALS; ELECTROMAGNETIC RADIATION; FABRICATION; LASERS; MIRRORS; OPTICS; PERMEABILITY; PERMITTIVITY; POLARIZATION; REFLECTION; RESONANCE; RESONATORS; SENSITIVITY; SHAPE; SYMMETRY

Citation Formats

Azad, Abul Kalam, Shchegolkov, Dmitry Yu, Chen, Houtong, Taylor, Antoinette, Smirnova, E I, and O' Hara, John F. Perfect terahertz absorber using fishnet based metafilm. United States: N. p., 2009. Web.
Azad, Abul Kalam, Shchegolkov, Dmitry Yu, Chen, Houtong, Taylor, Antoinette, Smirnova, E I, & O' Hara, John F. Perfect terahertz absorber using fishnet based metafilm. United States.
Azad, Abul Kalam, Shchegolkov, Dmitry Yu, Chen, Houtong, Taylor, Antoinette, Smirnova, E I, and O' Hara, John F. 2009. "Perfect terahertz absorber using fishnet based metafilm". United States. doi:. https://www.osti.gov/servlets/purl/979674.
@article{osti_979674,
title = {Perfect terahertz absorber using fishnet based metafilm},
author = {Azad, Abul Kalam and Shchegolkov, Dmitry Yu and Chen, Houtong and Taylor, Antoinette and Smirnova, E I and O' Hara, John F},
abstractNote = {We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2009,
month = 1
}

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  • Abstract not provided.
  • We present two designs of robust, easy to manufacture meta material-based films of sub-wavelength thickness capable of full absorption of the incident terahertz (THz) radiation at certain frequencies. Both designs can be either made polarization sensitive, or have 90{sup o} rotation symmetry, which works equally well for waves of any polarization provided the incident angle is zero. All our designs work for a wide range of angles of incidence, and even if the films are optimized for normal incidence the absorption remains greater than 99% for angles up to {approx}35{sup o} in the TE and {approx}65{sup o} in the TMmore » case. In the first design the maximum absorption frequency shifts considerably with angle, and in the second design the maximum absorption frequency remains almost the same at any angle. Theory, simulation data, and recent experimental results are all in a good agreement, and will be reported in the presentation. Having a low heat capacity these absorbers combined with thermo detectors can be utilized for precise frequency-selective detection of THz radiation.« less
  • Ultrafast control of the polarization state of light may enable a plethora of applications in optics, chemistry and biology. However, conventional polarizing elements, such as polarizers and waveplates, are either static or possess only gigahertz switching speeds. Here, with the aid of high-mobility indium-doped cadmium oxide (CdO) as the gateway plasmonic material, we realize a high-quality factor Berreman-type perfect absorber at a wavelength of 2.08 μm. On sub-bandgap optical pumping, the perfect absorption resonance strongly redshifts because of the transient increase of the ensemble-averaged effective electron mass of CdO, which leads to an absolute change in the p-polarized reflectance frommore » 1.0 to 86.3%. As a result, by combining the exceedingly high modulation depth with the polarization selectivity of the perfect absorber, we experimentally demonstrate a reflective polarizer with a polarization extinction ratio of 91 that can be switched on and off within 800 fs.« less
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