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Proceedings Paper

Coherent imaging at 2.4 THz with a CW quantum cascade laser transmitter
Author(s): Andriy A. Danylov; Thomas M. Goyette; Jerry Waldman; Michael J. Coulombe; Andrew J. Gatesman; Robert H. Giles; Xifeng Qian; Neelima Chandrayan; Shivashankar Vangala; Krongtip Termkoa; William D. Goodhue; William E. Nixon
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Paper Abstract

A coherent transceiver using a THz quantum cascade laser as the transmitter and an optically pumped molecular laser as the local oscillator has been used, with a pair of Schottky diode mixers in the receiver and reference channels, to acquire high-resolution images of fully illuminated targets, including scale models. Phase stability of the received signal, sufficient to allow coherent image processing of the rotating target (in azimuth and elevation), was obtained by frequency-locking the TQCL to the free-running, highly stable optically pumped molecular laser. While the range to the target was limited by the available TQCL power (several hundred microwatts) and reasonably strong indoor atmospheric attenuation at 2.408 THz (2.0 dB/m at 40% RH), the coherence length of the QCL transmitter will allow coherent imaging over distances up to several hundred meters. In contrast to non-coherent heterodyne detection, coherent imaging allows signal integration over time intervals considerably longer than the reciprocal of the source, or signal bandwidth, with consequent improvement in the signal-to-noise ratio. Image data obtained with the system will be presented.

Paper Details

Date Published: 19 February 2010
PDF: 8 pages
Proc. SPIE 7601, Terahertz Technology and Applications III, 760105 (19 February 2010); doi: 10.1117/12.843197
Show Author Affiliations
Andriy A. Danylov, Univ. of Massachusetts Lowell (United States)
Thomas M. Goyette, Univ. of Massachusetts Lowell (United States)
Jerry Waldman, Univ. of Massachusetts Lowell (United States)
Michael J. Coulombe, Univ. of Massachusetts Lowell (United States)
Andrew J. Gatesman, Univ. of Massachusetts Lowell (United States)
Robert H. Giles, Univ. of Massachusetts Lowell (United States)
Xifeng Qian, Univ. of Massachusetts Lowell (United States)
Neelima Chandrayan, Univ. of Massachusetts Lowell (United States)
Shivashankar Vangala, Univ. of Massachusetts Lowell (United States)
Krongtip Termkoa, Univ. of Massachusetts Lowell (United States)
William D. Goodhue, Univ. of Massachusetts Lowell (United States)
William E. Nixon, U.S. Army National Ground Intelligence Ctr. (United States)


Published in SPIE Proceedings Vol. 7601:
Terahertz Technology and Applications III
Laurence P. Sadwick; Creidhe M. M. O'Sullivan, Editor(s)

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