In this paper, we present results from our theoretical and experimental exploration of tailoring the absorption spectrum of a type of metamaterial absorber through manipulating the symmetricity and uniformity of the metallic submicron particle array on the top layer. The absorber under study is a metal-insulator-metal (MIM) trilayer structure made up of a top layer of engineered metallic submicron particles, a middle insulator spacer layer and an opaque ground metal reflector layer. We first studied the structure with a top layer consisting of a uniform array of raindrop-shaped gold (Au) submicron disks. We designed the raindrop shape with a reflectional symmetry on the 45° line. We compared the spectrum generated with that of a similar structure but the top layer which is filled with uniformly arranged circular submicron discs. It has been well reported that an array of circular particles each with both reflectional and rotational symmetries usually generates a spectrum with one absorption spike. By changing the circular shape to raindrop shape, the MIM absorber has been predicted to generate two absorption peaks with significantly broadened absorption bandwidth. Subsequently, we found that even wider spectra could be achieved if the top layer is built with a periodic arrangement of the unit cells containing differently sized raindrop-shaped disks. This leads to a wider bandwidth of higher than 50% absorbance ranging from 2.80 μm to 3.90 μm.
|Original language||English (US)|
|Title of host publication||Physics and Simulation of Optoelectronic Devices XXVIII|
|Editors||Bernd Witzigmann, Marek Osinski, Yasuhiko Arakawa|
|State||Published - 2020|
|Event||Physics and Simulation of Optoelectronic Devices XXVIII 2020 - San Francisco, United States|
Duration: Feb 3 2020 → Feb 6 2020
|Name||Proceedings of SPIE - The International Society for Optical Engineering|
|Conference||Physics and Simulation of Optoelectronic Devices XXVIII 2020|
|Period||2/3/20 → 2/6/20|
Bibliographical noteFunding Information:
The work is supported by the Grant-in-Aid award (#174244) from the University of Minnesota. Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network (NNCI) under Award Number ECCS-1542202.
© 2020 SPIE.
Copyright 2020 Elsevier B.V., All rights reserved.
- and submicron-scale
- infrared absorber