There is a continued interest in the terahertz (THz) spectral range due to potential applications in spectroscopy
and imaging. Real-time imaging in this spectral range has been demonstrated using microbolometer technology with
external illumination provided by quantum cascade laser based THz sources. To achieve high sensitivity, it is
necessary to develop microbolometer pixels using enhanced THz absorbing materials. Metal films with thicknesses
less than the skin depth for THz frequencies can efficiently absorb THz radiation. However, both theoretical
analysis and numerical simulation show that the maximum THz absorption of the metal films is limited to 50%.
Recent experiments carried out using a series of Cr and Ni films with different thicknesses showed that absorption
up to the maximum value of 50% can be obtained in a broad range of THz frequencies. A further increase in
absorption requires the use of resonant structures. These metamaterial structures consist of an Al ground plane, a
SiO<sub>2</sub> dielectric layer, and a patterned Al layer. Nearly 100% absorption at a specific THz frequency is observed,
which strongly depends on the structural parameters. In this paper, the progress in the use of thin metal films and
metamaterial structures as THz absorbers will be described.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gamani Karunasiri ; Fabio Alves ; Dragoslav Grbovic and Brian Kearney
"Identification of nano-scale films for THz sensing", Proc. SPIE 8373, Micro- and Nanotechnology Sensors, Systems, and Applications IV, 837326 (May 1, 2012); doi:10.1117/12.918624; http://dx.doi.org/10.1117/12.918624