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Proceedings Paper

Terahertz near-field probe incorporating a [lambda]/100 aperture for time-domain spectroscopy and imaging
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Paper Abstract

Achieving high spatial resolutions for imaging with terahertz (THz) waves requires near-field probes, such as a sub-wavelength aperture probe. Bethe’s theory of transmission through a sub-wavelength aperture of size a predicts that the transmitted electric field scales as Eαa3. This strong dependence limits the size of apertures that can be employed and hence the spatial resolution. This dependence however changes for the evanescent field components in very close proximity (~1μm for THz waves) to the aperture, as shown by electromagnetic simulations. To exploit this effect in a THz near-field probe, we developed a photoconductive THz near-field detector structure, which incorporates a thinned photo-conductive detector region and a distributed Bragg reflector between the detector and the aperture plane. Near-field probes are manufactured with different aperture sizes to investigate transmission of THz pulses through apertures as small as 3μm. The experimental results confirm that the transmitted field amplitude, and therefore the sensitivity, increases by about one order of magnitude for the new probes. A 3μm aperture probe with a spatial resolution of λ/100 at 1THz is demonstrated.

Paper Details

Date Published: 31 January 2014
PDF: 7 pages
Proc. SPIE 8993, Quantum Sensing and Nanophotonic Devices XI, 89931D (31 January 2014); doi: 10.1117/12.2039364
Show Author Affiliations
Alexander J. Macfaden, Univ. College London (United Kingdom)
John L. Reno, Sandia National Labs. (United States)
Igal Brener, Sandia National Labs. (United States)
Oleg Mitrofanov, Univ. College London (United Kingdom)
Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 8993:
Quantum Sensing and Nanophotonic Devices XI
Manijeh Razeghi; Eric Tournié; Gail J. Brown, Editor(s)

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