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Applied Optics

Applied Optics

APPLICATIONS-CENTERED RESEARCH IN OPTICS

  • Editor: Joseph N. Mait
  • Vol. 53, Iss. 13 — May. 1, 2014
  • pp: 2886–2891

Laser-generated broadband antireflection structures for freeform silicon lenses at terahertz frequencies

A. Brahm, S. Döring, A. Wilms, G. Notni, S. Nolte, and A. Tünnermann  »View Author Affiliations


Applied Optics, Vol. 53, Issue 13, pp. 2886-2891 (2014)
http://dx.doi.org/10.1364/AO.53.002886


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Abstract

We present a flexible technology to generate broadband antireflection (AR) structures for the terahertz (THz) frequency range on planar and curved surfaces of silicon optics. Ultrashort laser pulses are used to ablate the surface to form a pattern of conical pillars with a period of 30 μm. These subwavelength structures act as an effective medium with gradual transition of the refractive index from air to silicon, which reduces the Fresnel reflection losses. The characterization with the THz time-domain spectroscopy system shows an AR effect for a frequency range of 0.1–1.5 THz with a maximum enhancement of the spectral amplitude by ca. 32% at 0.4 THz for planar surfaces. In addition, we demonstrate laser-generated AR structures on convex silicon lenses of both photoconductive emitter and detector devices. Here, the THz pulse amplitude can be increased by about 28%, and single frequencies even show an improvement of the spectral amplitude up to 58%.

© 2014 Optical Society of America

OCIS Codes
(140.3390) Lasers and laser optics : Laser materials processing
(140.7090) Lasers and laser optics : Ultrafast lasers
(310.1210) Thin films : Antireflection coatings
(300.6495) Spectroscopy : Spectroscopy, teraherz
(050.6624) Diffraction and gratings : Subwavelength structures

ToC Category:
Lasers and Laser Optics

History
Original Manuscript: February 4, 2014
Revised Manuscript: March 18, 2014
Manuscript Accepted: April 3, 2014
Published: April 29, 2014

Citation
A. Brahm, S. Döring, A. Wilms, G. Notni, S. Nolte, and A. Tünnermann, "Laser-generated broadband antireflection structures for freeform silicon lenses at terahertz frequencies," Appl. Opt. 53, 2886-2891 (2014)
http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-53-13-2886


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References

  1. D. Grischkowsky, S. Keiding, M. van Exter, and C. Fattinger, “Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors,” J. Opt. Soc. Am. B 7, 2006–2015 (1990). [CrossRef]
  2. D. M. Mittleman, S. Hunsche, L. Boivin, and M. C. Nuss, “T-ray tomography,” Opt. Lett. 22, 904–906 (1997). [CrossRef]
  3. B. Ferguson, S. Wang, D. Gray, D. Abbot, and X. C. Zhang, “T-ray computed tomography,” Opt. Lett. 27, 1312–1314 (2002). [CrossRef]
  4. B. Ferguson and X. C. Zhang, “Materials for terahertz science and technology,” Nat. Mater. 1, 26–33 (2002). [CrossRef]
  5. Y. C. Shen, T. Lo, P. F. Taday, B. E. Cole, W. R. Tribe, and M. C. Kemp, “Detection and identification of explosives using terahertz pulsed spectroscopic imaging,” Appl. Phys. Lett. 86, 241116 (2005). [CrossRef]
  6. C. Jansen, S. Wietzke, O. Peters, M. Scheller, N. Vieweg, M. Salhi, N. Krumbholz, C. Jördens, T. Hochrein, and M. Koch, “Terahertz imaging: applications and perspectives,” Appl. Opt. 49, E48–E57 (2010). [CrossRef]
  7. C. Brückner, B. Pradarutti, R. Müller, S. Riehemann, G. Notni, and A. Tünnermann, “Design and evaluation of a THz time domain imaging system using standard optical design software,” Appl. Opt. 47, 4994–5006 (2008). [CrossRef]
  8. J. Dai, J. Zhang, W. Zhang, and D. Grischkowsky, “Terahertz time-domain spectroscopy characterization of the far-infrared absorption and index of refraction of high-resistivity, float-zone silicon,” J. Opt. Soc. Am. B 21, 1379–1386 (2004). [CrossRef]
  9. A. Brahm, M. Kunz, S. Riehemann, G. Notni, and A. Tünnermann, “Volumetric spectral analysis of materials using terahertz-tomography techniques,” Appl. Phys. B 100, 151–158 (2010). [CrossRef]
  10. M. van Exter and D. R. Grischkowsky, “Characterization of an optoelectronic terahertz beam system,” IEEE Trans. Microwave Theor. Tech. 38, 1684–1691 (1990). [CrossRef]
  11. M. Wichmann, A. S. Mondol, N. Kocic, S. Lippert, T. Probst, M. Schwerdtfeger, S. Schumann, T. Hochrein, P. Heidemeyer, M. Bastian, G. Bastian, and M. Koch, “Terahertz plastic compound lenses,” Appl. Opt. 52, 4186–4191 (2013). [CrossRef]
  12. K. Kawase and N. Hiromoto, “Terahertz-wave antireflection coating on Ge and GaAs with fused quartz,” Appl. Opt. 37, 1862–1866 (1998). [CrossRef]
  13. A. J. Gatesman, J. Waldman, M. Ji, C. Musante, and S. Yngvesson, “An anti-reflection coating for silicon optics at terahertz frequencies,” IEEE Microwave Guided Wave Lett. 10, 264–266 (2000). [CrossRef]
  14. I. Hosako, “Multilayer optical thin films for use at terahertz frequencies: method of fabrication,” Appl. Opt. 44, 3769–3773 (2005). [CrossRef]
  15. C. Brückner, T. Käsebier, B. Pradarutti, S. Riehemann, G. Notni, and A. Tünnermann, “Broadband antireflective structures applied to high resistive float zone silicon in the THz spectral range,” Opt. Express 17, 3063–3077 (2009). [CrossRef]
  16. R. Datta, C. D. Munson, M. D. Niemack, J. J. McMahon, J. Britton, E. J. Wollack, J. Beall, M. J. Devlin, J. Fowler, P. Gallardo, J. Hubmayr, K. Irwin, L. Newburgh, J. P. Nibarger, L. Page, M. A. Quijada, B. L. Schmitt, S. T. Staggs, R. Thornton, and L. Zhang, “Large-aperture wide-bandwidth antireflection-coated silicon lenses for millimeter wavelengths,” Appl. Opt. 52, 8747–8757 (2013). [CrossRef]
  17. P. B. Clapham and M. C. Hutley, “Reduction of lens reflection by the ‘moth eye’ principle,” Nature 244, 281–282 (1973). [CrossRef]
  18. J. Y. L. Ma and L. C. Robinson, “Night moth eye window for the millimetre and sub-millimetre wave region,” Opt. Acta 30, 1685–1695 (1983). [CrossRef]
  19. W. H. Southwell, “Pyramid-array surface-relief structures producing antireflection index matching on optical surfaces,” J. Opt. Soc. Am. A 8, 549–553 (1991). [CrossRef]
  20. P. Lalanne and D. Lemercier-Lalanne, “Depth dependence of the effective properties of subwavelength gratings,” J. Opt. Soc. Am. A 14, 450–458 (1997). [CrossRef]
  21. T. K. Gaylord, W. E. Baird, and M. G. Moharam, “Zero-reflectivity high spatial-frequency rectangular-groove dielectric surface-relief gratings,” Appl. Opt. 25, 4562–4567 (1986). [CrossRef]
  22. S. Döring, S. Richter, A. Tünnermann, and S. Nolte, “Evolution of hole depth and shape in ultrashort pulse deep drilling in silicon,” Appl. Phys. A 105, 69–74 (2011). [CrossRef]
  23. R. J. B. Dietz, M. Gerhard, D. Stanze, M. Koch, B. Sartorius, and M. Schell, “THz generation at 1.55  μm excitation: six-fold increase in THz conversion efficiency by separated photoconductive and trapping regions,” Opt. Express 19, 25911–25917 (2011). [CrossRef]

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