Towards broadband THz spectroscopy and analysis of sub-wavelength-size biological samples

Abstract

The Terahertz (THz) technology has now reached a level of maturation, which allows its uses beyond its core domains of application (telecom and imaging for security or healthcare). Vibrational spectroscopy in the THz range is employed in various fields and is specifically promising in (µ)biology. Indeed, the probed vibrational states extend over several nanometers and give a signature of the sample 3D structure at the nanoscale. This is particularly salient for macromolecules (proteins, DNA and RNA strands etc.) since, on one hand, their 3D structure is very difficult to probe in physiological condition with other techniques, and on the other hand, this structure determines their function and is consequently of utmost importance for the living. A major hurdle still arises when applying THz spectroscopy on biological or macromolecular samples. The samples are generally smaller than the THz wavelength, which requires concentrating the THz field in the sample. Solutions aimed at tackling this challenge by using µ/nano technology of THz field concentration and a proper data analysis will be presented.

Towards broadband THz spectroscopy and analysis of subwavelength size biological samples

“…We improved the first technology based on laser etching of copper plate to a more rigid and technology compatible material: silicon covered by gold [22,23]. Thanks to this new technology [24], we succeed in making 20-µm-wide, 300-µm-thick and 1-cm-long waveguide going from a factor 5 [21] in field enhancement to a factor 30 [22,23]. Consequently, we were able to perform TDS spectroscopy of small amount of powder samples.…”