Demonstration of broadband anti-reflection coating on sapphire based on mm-wave sub-wavelength structures

R. Takaku, T. Matsumura, H. Sakurai, K. Konishi, H. Imada, S. Hanany, K. Young, Q. Wen, Y. Sakurai, N. Katayama, K. Mitsuda, N. Yamasaki, K. Komatsu, H. Ishino, J. Yumoto, M. Kuwata-Gonokami

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We developed broadband anti-reflection coating using subwavelength structures on C-cut sapphire. We ablated sapphire using a femtosecond pulsed laser. We have developed a scanning strategy to make the deep structure. We successfully fabricated two saphire samples with arrays of the pyramidal structures over a machined diameter of 34.5 mm. The dimensions of the pyramid are a pitch of 0.54 mm and a height of 2.1 mm. The slope of the pyramid was fine tuned to be a bell shape, which could give better broadband anti-reflection performance compared to other shapes we investigated. The processing time is 10.5 hours for each sample. The number of the fabricated structures are more than 3000 for each samples, and we did not observe any loss of the structure due to the fabrication process. Transmittance measurements agreed with the predictions based on the measured structure shape and we achieved larger than 90% between 40 and 180 GHz. We will discuss the implication of this demonstrated performance in relation to mm-wave quasi-optical element, specifically in the context of astrophysical measurements of the cosmic microwave background radiation.

Original languageEnglish
Title of host publicationIRMMW-THz 2019 - 44th International Conference on Infrared, Millimeter, and Terahertz Waves
PublisherIEEE Computer Society
ISBN (Electronic)9781538682852
DOIs
Publication statusPublished - Sep 2019
Event44th International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2019 - Paris, France
Duration: Sep 1 2019Sep 6 2019

Publication series

NameInternational Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz
Volume2019-September
ISSN (Print)2162-2027
ISSN (Electronic)2162-2035

Conference

Conference44th International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2019
CountryFrance
CityParis
Period9/1/199/6/19

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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  • Cite this

    Takaku, R., Matsumura, T., Sakurai, H., Konishi, K., Imada, H., Hanany, S., Young, K., Wen, Q., Sakurai, Y., Katayama, N., Mitsuda, K., Yamasaki, N., Komatsu, K., Ishino, H., Yumoto, J., & Kuwata-Gonokami, M. (2019). Demonstration of broadband anti-reflection coating on sapphire based on mm-wave sub-wavelength structures. In IRMMW-THz 2019 - 44th International Conference on Infrared, Millimeter, and Terahertz Waves [8873910] (International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz; Vol. 2019-September). IEEE Computer Society. https://doi.org/10.1109/IRMMW-THz.2019.8873910