Situées entre l'infrarouge et les micro-ondes, les ondes dites "terahertz" (THz) ont les propriétés de passer aussi bien à travers la peau et les vêtements que les papiers, le bois, le carton ou encore le plastique. Autant d'atouts qui permettent d'envisager de multiples applications dans les secteurs de l'imagerie médicale, de la spectroscopie, de...
The terahertz radiation produced by a 2-color femtosecond laser scheme strongly saturates and develops an oscillatory behavior with increasing power of the driving femtosecond laser pulses. This is explained by the formation of a plasma channel due to filamentation. Due to dispersion inside the filament and the Gouy phase shift, the phase differenc...
Published in Chinese Science Bulletin
Gyrotrons are the most powerful terahertz sources and have potential applications in many areas. A terahertz gyrotron oscillator with a pulsed solenoid producing up to an 8 T magnetic field has been designed, constructed and tested. In a 7.96 T magnetic field, 3 kW output power radiations at 0.22 THz frequency have been generated.
2009 IEEE MTT-S International Microwave Symposium, IMS 2009. Boston, MA, USA, 7 - 12 June 2009
Le phénomène de filamentation laser apparaît spontanément dans un faisceau laser infra-rouge se propageant dans l'air si sa puissance crête excède quelques Gigawatts. À ce régime d'intensité le faisceau s'effondre sur lui même par effet Kerr et un équilibre dynamique s'installe entre la diffraction, l'effet Kerr et la défocalisation par l'air ionis...
Le travail de thèse a porté de façon générale sur l'étude des transitions dans les hétérostructures à cascade quantique. Deux types de structures ont été étudiés, le laser émettant dans la gamme des THz et le détecteur moyen infrarouge. Cette étude a été menée en champ magnétique appliqué perpendiculairement ou parallèlement aux couches des hétéros...
The transition-Cherenkov terahertz radiation from a femtosecond laser filament in air is enhanced by three orders of magnitude in the presence of a longitudinal static electric field, while the radiation pattern and the polarization remain the same. An amplified longitudinal electron current inside the filament is responsible for this amplified ter...
We observe a 3 order of magnitude enhancement of the terahertz energy radiated by a femtosecond pulse undergoing filamentation in air in the presence of a static electric field. Measurements of terahertz pulse duration, spectrum, polarization, and radiation pattern elucidate the physical processes responsible for this radiation. A theoretical model...
We examine the generation of terahertz by optical rectification of fundamental infrared beam with its first harmonic in ionized air. From polarization measurements we identify an important, yet so far unreported cross term (X(3)xyxy + X(3)xyyx) of the nonlinear susceptibility tensor. Omission of this term leads to an error by a factor 10^6 of the T...
Published in Journal of Electronic Materials
In recent years, terahertz (THz) sources between 0.1 THz and 10 THz have attracted much attention for imaging and sensing applications. THz emission from radiative transitions in impurity states has been demonstrated in Si and Ge devices by either electrical or optical pumping. Compared to Si as the material for THz emission, the wide-band-gap mate...
