Post-doctoral position in time-domain terahertz imaging, Georgia Tech-CNRS laboratory, Metz, France

We offer a 14-month postdoc position at the Georgia Tech-CNRS lab (UMI 2958) in Metz, France. Start
date should be between January 1 and March 31, 2021. Work will be performed in collaboration with
LEM3 (UMR 7239) also located in Metz, France.
Georgia Tech-CNRS uses a THz-Time Domain Spectroscopy (THz-TDS) system to investigate material
properties or damage. The postdoc position will focus on the analysis of damage propagation in glass fiber
reinforced composites, used in the automotive industry, when subjected to mechanical strain. The goal
of the project is to identify indicators of damage criticality from THz measurements. The work will involve
a combination of THz measurements, signal/image processing, and micro-computed tomography
measurements. The latter will be performed at the LEM3 partner lab. Depending on progress, there may
be an opportunity to study other types of samples.


Inquiries should be sent by email to Dr. Alexandre Locquet (alocquet@georgiatech-metz.fr) and Prof.
David Citrin (david.citrin@ece.gatech.edu). Candidates should hold a doctoral degree in a relevant field
including, but not limited to, Physics, Electrical Engineering, Mechanical Engineering, or Materials Science.


About us:
The Georgia Tech-CNRS laboratory is the result of a strategic alliance between the Georgia Institute of
Technology and the CNRS. The Photonics and Terahertz group is part of GeorgiaTech-CNRS and focuses
on terahertz imaging and laser dynamics. The THz lab is based on a THz-TDS imager with reflection,
transmission, and angular-dependent capabilities, as well as a large translation stages. The lab has in situ
imaging under controlled temperature and tensile/compressive stress. In the context of THz NDE, the
group has investigated glass- [1,2] and carbon fiber- reinforced polymers [3,4], as well as composites
involving both fiber types [5]. It has studied thin polymer coating layers on steel and underlying corrosion
[6] as well as multi-layer art paintings [7,8]. Finally, the group has helped pave the way for the use in THz
imaging of two blind signal processing techniques, viz. sparse deconvolution [9] and autoregressive
spectral extrapolation [10].


References:
[1] J. Dong, B. Kim, A. Locquet, P. McKeon, N. Declerq, D.S. Citrin, “Nondestructive evaluation of forced delamination
in glass fiber-reinforced composites by terahertz and ultrasonic waves”, Compos. Part B 79, 667(2015).
[2] J. Dong, A. Locquet, and D.S. Citirn, "Enhanced Terahertz Imaging of Small Forced Delamination in Woven Glass
Fiber-reinforced Composites with Wavelet De-noising", Journal of Infrared, Millimeter, and Terahertz Waves 37, 289
(2016).
[3] J.Dong, P. Pomerade, L. Chemami, A. Locquet, F. Meraghni, N. Declercq, D.S. Citrin, "Visualization of carbon fiber-
reinforced composites using polarization-sensitive terahertz imaging", NDT&E Int. 99, 72 (2018).
[4] Pascal Pomarède, Lynda Chehami, Nico F Declercq, Fodil Meraghni, Junliang Dong, Alexandre Locquet, DS Citrin,
“Application of Ultrasonic Coda Wave Interferometry for Micro-cracks Monitoring in Woven Fabric Composites”, J.
Nondestruct. Eval. 38, 26 (2019).
[5] J. Dong, A.Locquet. N. Declerq, and D.S. Citrin, "Polarization-resolved terahertz imaging of intra- and inter-
laminar damages in hybrid fiber-reinforced composite laminate subject to low-velocity impact", Compos. Part. B 92,
167 (2016).
[6] J. Dong, A. Locquet, and D. S. Citrin, "Terahertz Quantitative Nondestructive Evaluation of Failure Modes in
Polymer-Coated Steel", IEEE J. Sel. Top. Quantum Electron. 23, 8400207 (2017).

[7] J. Dong, J. Bianca Jackson, M. Melis, D. Giovannacci, G.C. Walker, A. Locquet, J.W. Bowen, and D. S. Citrin,
“Terahertz Frequency-Wavelet Domain Deconvolution for Stratigraphic and Subsurface Investigation of Art
Painting”, Opt. Express 24, 26972 (2016).
[8] J. Dong, A. Locquet, M. Melis, and D. S. Citrin, « Global mapping of stratigraphy of an old-master painting using
sparsity-based terahertz reflectometry”, Sci. Rep. 7, 15098 (2017).
[9] J. Dong, X. Wu, A. Locquet, and D.S. Citrin, “Teraherthz super-resolution stratigraphic characterization of multi-
layered structures using sparse deconvolution”, IEEE Trans. THz Sci. Technol. 3, 260 (2017).
[10] J. Dong, A. Locquet, and D. S. Citrin, “Depth-resolution enhancement of terahertz deconvolution by
autoregressive spectral extrapolation”, Optics Letters 42, 1828 (2017).