Terahertz imaging through emissivity control
arXiv:2308.12047 · doi:10.1364/OPTICA.503936
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.
References in corpus (7)
- Transforming heat transfer with thermal metamaterials and devices
- Nanophotonic engineering of far-field thermal emitters
- Electronic modulation of infrared emissivity in graphene plasmonic resonators
- Controlling Thermal Emission by Parity-symmetric Fano Resonance of Optical Absorbers in Metasurfaces
- Observation of Non-Vanishing Optical Helicity in Thermal Radiation from Symmetry-Broken Metasurfaces
- Dynamic modulation of thermal emission -- a Tutorial
- Magnetic field-induced thermal emission tuning of InSb-based metamaterials in the terahertz frequency regime