Obiettivo
High-order harmonic generation (HG) is one of the promising ways to obtain short-wavelength source of coherent radiation. The objective of this project is to develop new approaches to high-order HG in order to achieve higher conversion efficiencies. This project is aimed at the development of
(i) the specular-geometry scheme for high-harmonic generation in a plasma created by superstrong femtosecond pulses on a solid surface and the improvement of the efficiency of frequency conversion due to surface electromagnetic waves;
(ii) the transmission-geometry scheme for coherent harmonic generation in a low-temperature plasma of optical breakdown and the determination of the main physical factors that limit the efficiency of frequency conversion in laser-produced plasmas;
(iii) plasma sources of coherent UV and XUV radiation based on harmonic generation and nonlinear-optical wave mixing;
(iv) a theory of nonlinear-optical processes in laser-produced plasmas in the field of intense ultrashort laser pulses with allowance for field-dependent electron-ion collisions and field-modified electron distribution function.
The proposed project includes the following main research activities:
(i) experiments on HG in femtosecond near-surface plasmas in reflection geometry aimed at revealing limitations on the highest harmonic order; polarization of harmonics, selection rules, and angular dependence revealing relativistic effects; the role of the plasma density profile; the role of ponderomotive effects on plasma dynamics and the plasma-vacuum interface; the role of SEW in HG efficiency;
(ii) experiments on HG and nonlinear-optical wave mixing in a low-temperature laser-produced plasma in transmission geometry on pico- and femtosecond time scale;
(iii) development of the theory of harmonic generation and frequency mixing in plasmas based on analytical and numerical solution of the kinetic equation for the electron distribution function; analysis of the role of excited atoms and ions with the use of classical and quantum models.
The research is supposed to be an essential step in understanding and raising the efficiency of HG and nonlinear-optical frequency conversion in plasma induced on solid targets by ultrashort laser pulses.
The main expected results can be summarized as follows:
(i) development of the basic principles of applying HG from plasmas produced near metal and dielectric solid surfaces in the field of femto- and picosecond laser pulses for designing sources of coherent short-wavelength radiation;
(ii) revealing basic physical mechanisms of HG and physical restrictions imposed on the efficiency of frequency conversion and the highest order of harmonics for various regimes of nonlinear-optical interaction including plasma wave excitation;
(iii) optimisation of HG in different regimes of laser-plasma interactions by an appropriate choice of the experimental geometry; target, phase-matching conditions, and delay time between pumping and probing, excitation of plasma waves.
Invito a presentare proposte
Data not availableMeccanismo di finanziamento
Data not availableCoordinatore
45117 Essen
Germania