22 ноября 2010 г

1. Peng Liu (Shanghai Institute of Optics and Fine Mechanics, China)

   ГЕНЕРАЦИЯ ВЫСОКИХ ГАРМОНИК И ТЕРАГЕРЦОВОГО ИЗЛУЧЕНИЯ СВЕРХКОРОТКИМ ИНТЕНСИВНЫМ ЛАЗЕРНЫМ ПОЛЕМ
   
   High-order harmonic generation (HHG) from molecules and atoms are investigated experimentally. We found that the modulation inversion of harmonic yield from carbon dioxide molecules with respect to the alignment can be altered dramatically by the intensity of the driving laser field. The laser field dependent inversion can be explained by the shift angular distribution of harmonic emission calculated with the strong field approximation model including a ground state depletion factor. Secondly, the quantum trajectories of harmonic generation from atoms can be controlled by the shaped laser field, with which the phase matching condition acts to select out quantum paths.
   THz generation from filament in air has been detected using the time domain spectroscopy. It is used to measure the carrier envelope phase of a Infrared few-cycle laser pulse (1.8 microns/12fs) from a home-made optical parametric amplifier system. The intensity and time domain spectra reveals the stabilized CEP for hours.
   

2. Zhinan Zeng (Shanghai Institute of Optics and Fine Mechanics, China)
   

   АТТОСЕКУНДНЫЕ ИМПУЛЬСЫ, ГЕНЕРИРУЕМЫЕ ДВУХЧАСТОТНЫМ ЛАЗЕРНЫМ ПОЛЕМ
   
   The creation of attosecond (as) extreme ultraviolet (XUV) pulses opens the route to time-resolved atomic physics since the electron motion around the atom is at the sub-femtosecond time scale. So far, the high order harmonic generation (HHG) is the mainly method to produce the attosecond pulse. The HHG can be generated when the atoms is exposed to a moderate laser field. By filtering a part of the HHG, the attosecond pulse trains or isolated attosecond pulse can be produced. In the HHG process, the electron motion is very sensitive to the waveform of the electric field. We investigate the process to produce the IAP, to shorten the pulse duration and so on, by using the two-color laser field.
   With 6fs/800nm+21.3fs/400nm two color laser field, an ultrabroad extreme ultraviolet supercontinuum spectrum with a 148 eV spectral width can be generated which directly creates an isolated 65 as pulse even without phase compensation. We also demonstrate that using of the two-color field provides compensation of the negative chirp in harmonic. A new scheme for generating isolated attosecond pulse using a chirped two-color laser field of multi-cycle duration is proposed. In contrast to previous techniques, this scheme is robust against the large variation of carrier-envelope phase.

   
   

 

Начало в 10.00, корп.1, конф.-зал

Тел. 8-(499)135-41-48, 8-(499)135-52-15