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Y. R. Shen University of California, Berkeley Optical rectification of intense laser pulses

Gerard Mourou University of Rochester Generation of picosecond electrical transients Time-resolved measurements with far-IR radiation

David Auston Columbia University, New York Picosecond pulses from photo- conductive switches (the Auston switch)

Daniel Grischkowsky Oklahoma State University Free-space THz transients Optical THz technology THz time-domain spectroscopy

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2424

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15.09.2008Terahertz Technologies and Biophotonics11

Geometry of a broadband THz antenna

Auston switch(1984)

Semiconductor substrate

+

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• Electrodes are defined on a semi-conductor surface by UV or e-beamlithography and metal evaporation.

• There is a bias applied across the electrodes.

• The photoconductive region between the electrodes is excited by a femtosecondlaser.

• The transient photocurrent leads to emission of THz radiation.

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THz image of a freshly cut and 48 hours old leaf

Hu and Nuss, Opt. Lett. 20, 1716 (1995)

THz transmission image of a Hershey bar

THz time delay image of a Hershey bar

Mittleman et al. Appl. Phys. B 68, 1085 (1999)

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Visual inspection: Nothing dangerous!

THz picture: hidden knife is visible.

[Source: QinetiQ, http://www.qinetiq.com]

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http://frhethz.physik.uni-freiburg.de

Mummified hand

THz-Transission at 0.16 THz

Lena Öhrström, P.D. Dr. Dr. Frank Rühli

Klinische PaläopathologieMedizinhistorisches Institut, Universität Zürich

X-ray

THz-pulse delay image

II

III

IV

L. Öhrström et al., submitted (2009)

11Monday, October 5, 2009

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