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1.6:1 bandwidth two-layer antireflection structure for silicon matched to the 190–310  GHz atmospheric window

Defrance, Fabien and Jung-Kubiak, Cecile and Sayers, Jack and Connors, Jake and deYoung, Clare and Hollister, Matthew I. and Yoshida, Hiroshige and Chattopadhyay, Goutam and Golwala, Sunil R. and Radford, Simon J. E. (2018) 1.6:1 bandwidth two-layer antireflection structure for silicon matched to the 190–310  GHz atmospheric window. Applied Optics, 57 (18). pp. 5196-5209. ISSN 0003-6935. doi:10.1364/AO.57.005196.

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Although high-resistivity, low-loss silicon is an excellent material for terahertz transmission optics, its high refractive index necessitates an antireflection treatment. We fabricated a wide-bandwidth, two-layer antireflection treatment by cutting subwavelength structures into the silicon surface using multi-depth deep reactive-ion etching (DRIE). A wafer with this treatment on both sides has <−20  dB (<1%) reflectance over 187–317 GHz at a 15° angle of incidence in TE polarization. We also demonstrated that bonding wafers introduce no reflection features above the −20  dB level (also in TE at 15°), reproducing previous work. Together these developments immediately enable construction of wide-bandwidth silicon vacuum windows and represent two important steps toward gradient-index silicon optics with integral broadband antireflection treatment.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Defrance, Fabien0000-0002-3746-5296
Sayers, Jack0000-0002-8213-3784
Chattopadhyay, Goutam0000-0001-7942-5025
Golwala, Sunil R.0000-0002-1098-7174
Additional Information:© 2018 Optical Society of America. Received 16 March 2018; revised 17 May 2018; accepted 22 May 2018; posted 22 May 2018 (Doc. ID 326119); published 19 June 2018. We performed this work at the California Institute of Technology, the Caltech Submillimeter Observatory Hilo office, the Harvard-Smithsonian Center for Astrophysics, and the MicroDevices Laboratory of the Jet Propulsion Laboratory (operated by the California Institute of Technology under a contract with the National Aeronautics and Space Administration). The authors thank A. Bose for early, pathfinding HFSS simulation work, K. McClure for contributions to the HFSS tolerancing simulations, K. Yee for performing the wafer-bonding steps, J. Wong for contributions to the test setup control code, E. Padilla for undertaking preparatory measurements of the two-layer structures, C.-Y. E. Tong for participation in the Fig. 14 alternate technique measurements, and T. Macioce for contributions to the text of the paper. C. de Young acknowledges support from an SAO Internship. D. Bisel, K. Deniston, and S. Stoll provided able administrative support. Funding: National Aeronautics and Space Administration (NASA) (NNX15AE01G).
Group:Astronomy Department
Funding AgencyGrant Number
Smithsonian Astrophysical ObservatoryUNSPECIFIED
Issue or Number:18
Classification Code:OCIS codes: (050.6624) Subwavelength structures; (220.4000) Microstructure fabrication; (220.4610) Optical fabrication; (310.6628) Subwavelength structures, nanostructures; (350.1260) Astronomical optics
Record Number:CaltechAUTHORS:20180705-143644278
Persistent URL:
Official Citation:Fabien Defrance, Cecile Jung-Kubiak, Jack Sayers, Jake Connors, Clare deYoung, Matthew I. Hollister, Hiroshige Yoshida, Goutam Chattopadhyay, Sunil R. Golwala, and Simon J. E. Radford, "1.6:1 bandwidth two-layer antireflection structure for silicon matched to the 190–310  GHz atmospheric window," Appl. Opt. 57, 5196-5209 (2018)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87565
Deposited By: George Porter
Deposited On:06 Jul 2018 14:41
Last Modified:15 Nov 2021 20:49

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