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The Simons Observatory: Metamaterial Microwave Absorber (MMA) and its Cryogenic Applications

Authors :
Xu, Zhilei
Chesmore, Grace E.
Adachi, Shunsuke
Ali, Aamir M.
Bazarko, Andrew
Coppi, Gabriele
Devlin, Mark
Devlin, Tom
Dicker, Simon R.
Gallardo, Patricio A.
Golec, Joseph E.
Gudmundsson, Jon E.
Harrington, Kathleen
Hattori, Makoto
Kofman, Anna
Kiuchi, Kenji
Kusaka, Akito
Limon, Michele
Matsuda, Frederick
McMahon, Jeff
Nati, Federico
Niemack, Michael D.
Sutariya, Shreya
Suzuki, Aritoki
Teply, Grant P.
Thornton, Robert J.
Wollack, Edward J.
Zannoni, Mario
Zhu, Ningfeng
Source :
Applied Optics, Vol. 60, Issue 4, pp. 864-874 (2021)
Publication Year :
2020

Abstract

Controlling stray light at millimeter wavelengths requires special optical design and selection of absorptive materials that should be compatible with cryogenic operating environments. While a wide selection of absorptive materials exists, these typically exhibit high indices of refraction and reflect/scatter a significant fraction of light before absorption. For many lower index materials such as commercial microwave absorbers, their applications in cryogenic environments are challenging. In this paper, we present a new tool to control stray light: metamaterial microwave absorber tiles. These tiles comprise an outer metamaterial layer that approximates a lossy gradient index anti-reflection coating. They are fabricated via injection molding commercially available carbon-loaded polyurethane (25\% by mass). The injection molding technology enables mass production at low cost. The design of these tiles is presented, along with thermal tests to 1 K. Room temperature optical measurements verify their control of reflectance to less than 1\% up to 65$\circ$ angles of incidence, and control of wide angle scattering below 0.01\%. The dielectric properties of the bulk carbon-loaded material used in the tiles is also measured at different temperatures, confirming that the material maintains similar dielectric properties down to 3 K.<br />Comment: 10 pages, 11 figures, published in Applied Optics, selected as "Editor's pick"

Details

Database :
arXiv
Journal :
Applied Optics, Vol. 60, Issue 4, pp. 864-874 (2021)
Publication Type :
Report
Accession number :
edsarx.2010.02233
Document Type :
Working Paper
Full Text :
https://doi.org/10.1364/AO.411711