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arXiv · 2308.12047

Terahertz imaging through emissivity control

Michal Mrnka·Harry Penketh·Ian R. Hooper·Sonal Saxena·Nicholas E. Grant·John D. Murphy·David B. Phillips·Euan Hendry
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Abstract

Adoption of terahertz technologies is hindered by the lack of cost-effective THz sources. Here we demonstrate a fundamentally new way to generate and control THz radiation, via spatio-temporal emissivity modulation. By patterning the optical photoexcitation of a surface-passivated silicon wafer, we locally control the free-electron density, and thereby pattern the wafer's emissivity in the THz part of the electromagnetic spectrum. We show how this unconventional source of controllable THz radiation enables a new form of incoherent computational THz imaging. We use it to image various concealed objects, demonstrating this scheme has the penetrating capability of state-of-the-art THz imaging approaches, without the requirement of femto-second pulsed laser sources. Furthermore, the incoherent nature of thermal radiation also ensures the obtained images are free of interference artifacts. Our spatio-temporal emissivity control paves the way towards a new family of long-wavelength structured illumination, imaging and spectroscopy systems.

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Michal Mrnka, Harry Penketh, Ian R. Hooper, Sonal Saxena, Nicholas E. Grant, John D. Murphy, David B. Phillips, Euan Hendry. 2023-08-23. Terahertz imaging through emissivity control. https://doi.org/10.1364/optica.503936

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