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Terahertz spectroscopy and imaging

 

Permanent staff:


Guilhem Gallot (CNRS)
 

Students:


Xiujun Zheng (PhD student)

   
 
 
 

THE TERAHERTZ RADIATION


 

The goal of the "terahertz" project is to develop new tools for imaging and analyzing biological systems with the help of terahertz (1012 Hz) radiation. The terahertz domain lies between the microwave and the far infrared domains. Recent developments of the terahertz electromagnetic wave technology now offer interesting applications in biological imaging. Among the involved advantages and in contrast with X-ray imaging, the sample does not suffer from terahertz imaging thanks to the low associated photon energy. We conceived and developed a new terahertz imaging technique, based on femtosecond-laser-driven photoconductive antenna to generate and detect terahertz radiation. It uses the specific physical and chemical properties of biological ions with respect to the terahertz radiation.

 

 

In particular, we demonstrated the significant application of Ionic Contrast Terahertz Imaging (ICTI) to excitable cells and the correlated ion fluxes, without staining or labelling. This technique provides quantitative measurements of ionic concentrations in both the intracellular and extracellular compartments and opens the way to direct noninvasive imaging of neurons during electrical, toxin, or thermal stresses. To increase the resolution, we adapted a near field technique based on subwavelength apertures. Furthermore, neuronal activity results from both a precise control of transient variations in ionic conductances and a much less studied water exchange between the extracellular matrix and the intraaxonal compartment. The developed ICTI technique associated with a full three-dimensional simulation of the axon-aperture near-field system allows a precise measurement of the axon geometry and therefore the direct visualization of neuron swelling induced by temperature change or neurotoxin poisoning. This technique should then provide grounds for the development of advanced functional neuroimaging methods based on diffusion anisotropy of water molecules. We also extended ICTI imaging to dynamical systems, recording living frog heart muscle dynamic electrical activity, recording ionic fluxes of spontaneously beating, non-stimulated and unstained auricular.  

Former participants:


Marianne Grognot (PhD 2016)
Antoine Wojdyla (PhD 2011)
Alexander Podzorov (PhD 2009)
Jean-Baptiste Masson (PhD 2007)

Research highlights:


"Observer les neurones grâce aux ondes térahertz"
La Recherche, Mai 2006. PDF
La Recherche, Janvier 2007. PDF

Terahertz links:


TERANAUTE association (in French): The "Teranaute" network brings together manufacturers and many French laboratories in the field of terahertz, aiming at identifying terahertz applications and developing terahertz sources and detectors.

 

Publications:


"Quantitative measurement of permeabilization of living cells by terahertz attenuated total reflection"
M. Grognot et G. Gallot
Appl. Phys. Lett. 107, 103702 (2015). PDF

"Attenuated internal reflection terahertz imaging"
A. Wojdyla et G. Gallot
Opt. Lett. 38, 112 (2013). PDF

"Diffraction from a subwavelength elliptic aperture: analytic approximate aperture fields"
J.-B. Masson et G. Gallot
J. Opt. Soc. Am. A 29, 2005 (2012). PDF

"Optical activity of metallic helices in the THz domain: a theoretical investigation."
F. Hache et G. Gallot
J. Opt. Soc. Am. B 29, 2675 (2012). PDF

"Brewster's angle silicon wafer terahertz linear polarizer"
A. Wojdyla et G. Gallot
Opt. Exp. 19, 14099 (2011). PDF

"Few femtosecond, few kiloampere electron bunch produced by a laser-plasma accelerator"
O. Lundh, J. Lim, C. Rechatin, L. Ammoura, A. Ben-Ismaïl, X. Davoine, G. Gallot, J.-P. Goddet, E. Lefebvre, V. Malka et J. Faure
Nature Physics 7, 219 (2011). PDF

"Density of states and vibrational modes of PDMS studied by terahertz time-domain spectroscopy"
A. Podzorov et G. Gallot
Chem. Phys. Lett. 495, 46 (2010). PDF

"Beam waist measurement for terahertz time-domain spectroscopy experiments"
A. Podzorov, A. Wojdyla et G. Gallot
Opt. Lett. 35, 901 (2010). PDF

"Extended Fano model of Extraordinary Electromagnetic Transmission through
subwavelength hole arrays in the terahertz domain"
J.-B. Masson, A. Podzorov et G. Gallot
Opt. Exp. 17, 15280 (2009). PDF

"Anomalies in the disappearance of the extraordinary electromagnetic transmission in subwavelength hole arrays"
J.-B. Masson, A. Podzorov et G. Gallot
Opt. Exp. 16, 4719 (2008). PDF

"Low-loss polymers for terahertz applications"
A. Podzorov et G. Gallot
Appl. Opt. 47, 3254 (2008). PDF

"A model for thermal exchange in axons during action potential propagation"
J.-B. Masson et G. Gallot
Eur. Biophys. J. 37, 1001 (2008). PDF

"True near field versus contrast near field imaging. II. imaging with a probe"
J.-B. Masson et G. Gallot
Opt. Exp. 15, 3078 (2007). PDF

"True near field versus contrast near field"
J.-B. Masson et G. Gallot
Opt. Exp. 14 , 11566 (2006). PDF

"Ionic contrast terahertz time resolved imaging of frog auricular heart muscle electrical activity"
J.-B. Masson, M.-P. Sauviat et G. Gallot
Appl. Phys. Lett. 89, 153904 (2006). PDF

"Ionic contrast terahertz near field imaging of axonal water fluxes"
J.-B. Masson, M.-P. Sauviat, J.-L. Martin et G. Gallot
PNAS 103 , 4808 (2006). PDF

"Coupling between surface plasmons in subwavelength hole arrays"
J.-B. Masson et G. Gallot
Phys. Rev. B 73, 121401(R) (2006). PDF

"Terahertz achromatic quarter-wave plate"
J.-B. Masson et G. Gallot
Opt. Lett. 31, 265 (2006). PDF

"Ultrashort laser pulses and ultrashort electron bunches generated in relativistic laser-plasma interaction"
J. Faure, Y. Glinec, G. Gallot et V. Malka
Phys. of Plasma 13, 056706 (2006). PDF