Broadband, millimeter-wave antireflection coatings for large-format, cryogenic aluminum oxide optics

A. Nadolski, J. D. Vieira, J. A. Sobrin, A. M. Kofman, P. A.R. Ade, Z. Ahmed, A. J. Anderson, J. S. Avva, R. Basu Thakur, A. N. Bender, B. A. Benson, L. Bryant, J. E. Carlstrom, F. W. Carter, T. W. Cecil, C. L. Chang, J. R. Cheshire, G. E. Chesmore, J. F. Cliche, A. CukiermanT. de Haan, M. Dierickx, J. Ding, D. Dutcher, W. Everett, J. Farwick, K. R. Ferguson, L. Florez, A. Foster, J. Fu, J. Gallicchio, A. E. Gambrel, R. W. Gardner, J. C. Groh, S. Guns, R. Guyser, N. W. Halverson, A. H. Harke-Hosemann, N. L. Harrington, R. J. Harris, J. W. Henning, W. L. Holzapfel, D. Howe, N. Huang, K. D. Irwin, O. Jeong, M. Jonas, A. Jones, M. Korman, J. Kovac, D. L. Kubik, S. Kuhlmann, C. L. Kuo, A. T. Lee, A. E. Lowitz, J. McMahon, J. Meier, S. S. Meyer, D. Michalik, J. Montgomery, T. Natoli, H. Nguyen, G. I. Noble, V. Novosad, S. Padin, Z. Pan, P. Paschos, J. Pearson, C. M. Posada, W. Quan, A. Rahlin, D. Riebel, J. E. Ruhl, J. T. Sayre, E. Shirokoff, G. Smecher, A. A. Stark, J. Stephen, K. T. Story, A. Suzuki, C. Tandoi, K. L. Thompson, C. Tucker, K. Vanderlinde, G. Wang, N. Whitehorn, V. Yefremenko, K. W. Yoon, M. R. Young

Research output: Contribution to journalArticlepeer-review

Abstract

We present two prescriptions for broadband (∼77 − 252 GHz), millimeter-wave antireflection coatings for cryogenic, sintered polycrystalline aluminum oxide optics: one for large-format (700 mm diameter) planar and plano–convex elements, the other for densely packed arrays of quasi-optical elements—in our case, 5 mm diameter half-spheres (called “lenslets”). The coatings comprise three layers of commercially available, polytetrafluoroethylene-based, dielectric sheet material. The lenslet coating is molded to fit the 150 mm diameter arrays directly, while the large-diameter lenses are coated using a tiled approach. We review the fabrication processes for both prescriptions, then discuss laboratory measurements of their transmittance and reflectance. In addition, we present the inferred refractive indices and loss tangents for the coating materials and the aluminum oxide substrate. We find that at 150 GHz and 300 K the large-format coating sample achieves (97 ± 2)% transmittance, and the lenslet coating sample achieves (94 ± 3)% transmittance.

Original languageEnglish (US)
Pages (from-to)3285-3295
Number of pages11
JournalApplied Optics
Volume59
Issue number10
DOIs
StatePublished - Apr 1 2020

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Engineering (miscellaneous)
  • Electrical and Electronic Engineering

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