Hyperspectral terahertz imaging with electro-optic dual combs and a FET-based detector

In this paper, a terahertz hyperspectral imaging architecture based on an electro-optic terahertz dual-comb source is presented and demonstrated. In contrast to single frequency sources, this multiheterodyne system allows for the characterization of the whole spectral response of the sample in parallel for all the frequency points along the spectral range of the system. This hence provides rapid, highly consistent results and minimizes measurement artifacts. The terahertz illumination signal can be tailored (in spectral coverage and resolution) with high fexibility to meet the requirements of any particular application or experimental scenario while maximizing the signal-to-noise ratio of the measurement. Besides this, the system provides absolute frequency accuracy and a very high coherence that allows for direct signal detection without inter-comb synchronization mechanisms, adaptive acquisition, or post-processing. Using a feld-efect transistor-based terahertz resonant 300GHz detector and the raster-scanning method we demonstrate the two-dimensional hyperspectral imaging of samples of diferent kinds to illustrate the remarkable capabilities of this innovative architecture. A proof-of-concept demonstration has been performed in which tree leaves and a complex plastic fragment have been analyzed in the 300 GHz range with a frequency resolution of 10 GHz.This project has received funding from the ATTRACT project funded by the EC under Grant Agreement 777222 and from the Spanish Ministry of Economy and Competitiveness under Project TEC2017-86271-R. The work has also been partially funded by the EU H2020 Celta project under Grant Agreement 675683 and the Foundation for Polish Science under grant IRA CENTERA. Viktor Krozer is thankful for partial financial support in the frame of the Chairs of Excellence program of the Universidad Carlos III, Madrid, Spain