Electron dynamics in dielectrics: from point defect to optical breakdown
Electron dynamics in dielectrics: from point defect to optical breakdown

From point defects to optical breakdown : depending upon the intensity, femtosecond lasers allow to study a broad range of phenomena, going from point defect generation: top, a model of self-trapped exciton in quartz, until optical breakdown (bottom): here image of an ablation crater, also in quartz (α-SiO2).



We study the excitation and relaxation processes in solids irradiated by intense ultrashort laser pulses. We focus our research on wide band gap dielectrics, either for their important applications in optics or electronics (SiO2, Al2O3, Diamant, MgO, CdWO4) or their fundamental interest (diamond, alkali halides…). 


The physical mechanisms investigated range from point defect formation up to optical breakdown, passing through high excitation density effects like exciton-exciton interaction in scintillating materials. 

Experimental approach : following the evolution of matter in real time

Lasers delivering ultrashort pulses are unique experimental tools to study solids, their advantage are twofold : 

  • generate a high and well defined excitation density in solids, 
  • allow time resolved experiments of pump-probe type using different diagnostics: interferometry, absorption, reflectivity, double pulse photoemission, and thus resolve the dynamics of excitation and relaxation processes. 


Our studies are at the border of at different domains: solid state physics, plasma physics, laser matter interaction in not-so-strong field. These fundamental research is the basis of important application fields: laser micro and nano machining at surface and in the bulk, laser induced modification of optical properties for optical fibers of wave plate, 3D direct microfabrication in transparent media, etc… 


The interaction of intense ultrashort pulses with matter is thus an important and growing research field. This is why it is mandatory to better understand the mechanism of propagation, energy deposition, damaging and optical breakdown. 


The experiments are carried out with the lasers servers of the SLIC laser facility at IRAMIS.

#3075 - Last update : 04/17 2019

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