Nonlinear high harmonic generation in atoms, molecules and nanostructures: A potential ultrafast and high energy light source;

In this paper,an introduction is give for the development and applications of ultrashort laser pulse technique in the fields of liquid molecule and ultrafast phenomema.

In this paper, the four developed periods for ultrafast lasers weve precented and their content, focus points were discusded.

Temperature field under ultra fast cooling (UFC) is simulated by finite-difference method.

In the authors' points,the main developing trends and research frontier in this field should be focused on the followingfour directions, first, high-power and large-energy laser crystals; second, practical mid-infraredlaser crystals; third, laser crystals emitting at UV and visible regions; fourth, ultrafast laser gainand amplifier media suitable for LD pumping.

Basing on both the spectra analysis of ultrafast lasers and the speckle statistical theory,we derive the autocorrelation function of ultrafast dynamic speckle intensity.