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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. 13 — Jun. 20, 2011
  • pp: 12759–12765

Causality-based method for determining the time origin in terahertz emission spectroscopy

Takeya Unuma, Yusuke Ino, Kai-Erik Peiponen, Erik M. Vartiainen, Makoto Kuwata-Gonokami, and Kazuhiko Hirakawa  »View Author Affiliations

Optics Express, Vol. 19, Issue 13, pp. 12759-12765 (2011)

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We propose a method for determining the time origin on the basis of causality in terahertz (THz) emission spectroscopy. The method is formulated in terms of the singly subtractive Kramers-Kronig relation, which is useful for the situation where not only the amplitude spectrum but also partial phase information is available within the measurement frequency range. Numerical analysis of several simulated and observed THz emission data shows that the misplacement of the time origin in THz waveforms can be detected by the method with an accuracy that is an order of magnitude higher than the given temporal resolutions.

© 2011 OSA

OCIS Codes
(000.3860) General : Mathematical methods in physics
(300.2140) Spectroscopy : Emission
(300.6495) Spectroscopy : Spectroscopy, teraherz

ToC Category:

Original Manuscript: April 26, 2011
Revised Manuscript: June 5, 2011
Manuscript Accepted: June 6, 2011
Published: June 16, 2011

Takeya Unuma, Yusuke Ino, Kai-Erik Peiponen, Erik M. Vartiainen, Makoto Kuwata-Gonokami, and Kazuhiko Hirakawa, "Causality-based method for determining the time origin in terahertz emission spectroscopy," Opt. Express 19, 12759-12765 (2011)

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  9. T. Unuma, Y. Ino, M. Kuwata-Gonokami, E. M. Vartiainen, K.-E. Peiponen, and K. Hirakawa, “Determination of the time origin by the maximum entropy method in time-domain terahertz emission spectroscopy,” Opt. Express 18(15), 15853–15858 (2010). [CrossRef] [PubMed]
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  12. Numerical results for K(δt) were insensitive to the way of cutting off the integration frequency range in Eq. (7).
  13. K(δt) becomes a periodic function of δt with a period equal to the original temporal length of ETHz(t).
  14. Even if ETHz(t) is recorded with non-flat sensitivity, causality should hold and thus our approach will also work. However, non-flat sensitivity will require a more complicated interpretation of THz signals.

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