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

Pedro Martín-Mateos, Dovilė Čibiraitė-Lukenskienė, Roberto Barreiro, Cristina de Dios, Alvydas Lisauskas, Viktor Krozer,  Pablo Acedo

https://www.nature.com/articles/s41598-020-71258-6

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 multi-heterodyne 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 flexibility 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 field-effect transistor-based terahertz resonant 300 GHz detector and the raster-scanning method we demonstrate the two-dimensional hyperspectral imaging of samples of different 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.

Abstract-All‐Dielectric Silicon Metasurface with Strong Subterahertz Toroidal Dipole Resonance

Dimitrios C. Zografopoulos  Antonio Ferraro  José Francisco Algorri  Pedro Martín‐Mateos  Braulio García‐Cámara  Aldo Moreno‐Oyervides  Viktor Krozer  Pablo Acedo  Ricardo Vergaz  José Manuel Sánchez‐Pena  Romeo Beccherelli,

https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.201900777

A single‐layer, all‐dielectric metasurface exhibiting a strong toroidal resonance in the low‐atmospheric loss radio window of the subterahertz W‐band is theoretically proposed and experimentally demonstrated. The metasurface is fabricated on a high‐resistivity floating‐zone silicon wafer by means of a single‐process, wet anisotropic etching technique. The properties of the toroidal mode of both the constituent dielectric elements and the metasurface are rigorously investigated by means of the multipole decomposition technique and full‐wave simulations. The experimental demonstration of such a compact, all‐silicon metasurface opens new venues of research in the investigation of toroidal modes and the engineering of functional millimeter‐wave components, which can be scaled to terahertz and higher frequencies of the electromagnetic spectrum

Abstract-Absolute-Frequency high-resolution real-time terahertz dual-comb spectrometer

Frederik Walla,  Borja Jerez,  Pedro Martín-Mateos, Cristina de Dios,  Pablo Acedo,

http://ieeexplore.ieee.org/document/8067218/


An absolute-frequency Terahertz dual frequency comb spectrometer for tunable, high-resolution and real-time rapid acquisition is presented. Two combs (probe and local oscillator) are electro-optically generated from the same line of a master optical frequency comb selected by optical injection locking. Photomixing each of these two initial optical combs with a coherent mode from the same master comb generates a narrow-linewidth Terahertz dual comb through difference frequency generation. The resulting dual-comb teeth are absolutely referenced to a RF clock standard.