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Proceedings Paper

Spectroscopy with electronic terahertz techniques
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Paper Abstract

We report gas absorption spectra and energetic material reflection spectra measured with an all-electronic terahertz (THz) spectrometer. This instrument uses phase-locked microwave sources to drive picosecond GaAs nonlinear transmission lines, enabling measurement of both broadband spectra and single lines with hertz-level precision, a new mode of operation not readily available with optoelectronic THz techniques. We take two approaches to coherent measurements: (1) spatially combining the freely propagating beams from two coherent picosecond pulse generators, or (2) using a more conventional coherent source/detector arrangement with sampling detectors. The first method employs a dual-source interferometer modulating each harmonic of one source with a precisely-offset harmonic from the other source - both sources being driven with stable phase-locked synthesizers - the resultant beat frequency can be low enough for detection by a standard composite bolometer. Room-temperature detection possibilities for the DSI include antenna-coupled Schottky diodes. Finally, we have recently introduced a reflectometer based on serrodyne modulation of a linearized delay line, using a technique that is process-compatible with pulse generator circuits.

Paper Details

Date Published: 9 September 1999
PDF: 9 pages
Proc. SPIE 3828, Terahertz Spectroscopy and Applications II, (9 September 1999); doi: 10.1117/12.361046
Show Author Affiliations
Daniel W. van der Weide, Univ. of Delaware (United States)
Janusz A. Murakowski, Univ. of Delaware (United States)
Fritz Keilmann, Max-Planck Institut fuer Biochemie (Germany)

Published in SPIE Proceedings Vol. 3828:
Terahertz Spectroscopy and Applications II
J. Martyn Chamberlain, Editor(s)

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