Accession Number:

ADA528771

Title:

Coherent Imaging at 2.4 THz with a CW Quantum Cascade Laser Transmitter

Descriptive Note:

Conference paper

Corporate Author:

NATIONAL GROUND INTELLIGENCE CENTER CHARLOTTESVILLE VA

Report Date:

2010-01-01

Pagination or Media Count:

9.0

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 dBm 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.

Subject Categories:

  • Lasers and Masers
  • Miscellaneous Detection and Detectors
  • Active and Passive Radar Detection and Equipment
  • Quantum Theory and Relativity

Distribution Statement:

APPROVED FOR PUBLIC RELEASE