Demonstration of anti-reflective structures over a large area for CMB polarization experiments

Ryota Takaku, Shaul Hanany, Yurika Hoshino, Hiroaki Imada, Hirokazu Ishino, Nobuhiko Katayama, Kunimoto Komatsu, Kuniaki Konishi, Makoto Kuwata Gonokami, Tomotake Matsumura, Kazuhisa Mitsuda, Haruyuki Sakurai, Yuki Sakurai, Qi Wen, Noriko Y. Yamasaki, Karl Young, Junji Yumoto

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

1 Scopus citations

Abstract

Sapphire, alumina, and silicon present the following characteristics that make them suitable as optical elements for millimeter and sub-millimeter applications: low-loss, high thermal conductivity at cryogenic temperatures, and high refractive index ∼3. However, the high index also leads to high reflection. We developed a technique to machine sub-wavelength structures (SWS) as a broadband anti-reflection coating on these materials through laser ablation. We describe here the status of our development: Transmission measurements of fabricated samples in a diameter of 34.5 mm agree with predictions, and we are now focusing on increasing the fabrication area with high processing rate. This is motivated by the need of ∼500 mm diameter optical elements for the next-generation cosmic microwave background polarization experiments. We show our large area machining method on the alumina and sapphire over an area of < 5200 mm2with the processing rate of < 4:0 mm3=min:, and the transmission measurements are consistent with the predictions.

Original languageEnglish (US)
Title of host publicationMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X
EditorsJonas Zmuidzinas, Jian-Rong Gao
PublisherSPIE
ISBN (Electronic)9781510636934
DOIs
StatePublished - 2020
EventMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X 2020 - Virtual, Online, United States
Duration: Dec 14 2020Dec 22 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume11453
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X 2020
CountryUnited States
CityVirtual, Online
Period12/14/2012/22/20

Bibliographical note

Funding Information:
We acknowledge the World Premier International Research Center Initiative (WPI), MEXT, Japan for support through Kavli IPMU. This work was supported by JSPS KAKENHI Grant Numbers JP17H01125, 19K14732, 18J20148, 18KK0083, and JSPS Core-to-Core Program, A. Advanced Research Networks. This work was also supported by the New Energy and Industrial Technology Development Organization (NEDO) project “Development of advanced laser processing with intelligence based on high-brightness and high efficiency laser technologies” by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “Photonics and Quantum Technology for Society 5.0” and by the Center of Innovation Program, from Japan Science and Technology Agency, JST.

Publisher Copyright:
© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

Keywords

  • CMB
  • broadband anti-reection
  • laser ablation
  • millimeter-wavelength

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