Femtosecond Laser Pulses Amplification Methods

The article presents methods for amplifying femtosecond laser pulses. A chirped-pulse amplification setup and a grating-based device are presented that can be used to amplify a chirped pulse with a total gain of up to 10¹¹. A typical block diagram of a chirped-pulse amplifier for producing high-power femtosecond pulses is described. The use of an amplifying system consisting of a multipass amplifier and amplification stages with a progressive increase in the diameter of the laser beam makes it possible to increase the pulse energy by a factor of 10⁸–10⁹, avoiding damage to the amplifying elements. The method of amplifying chirped pulses requires the use of diffraction gratings with sizes close to 1 m to amplify pulses up to energies of tens of J. In particular, the use of giant laser systems based on amplifying cascades containing neodymium glass plates is noted. A parametric method for amplifying femtosecond pulses is considered. The advantages and disadvantages of parametric amplification are discussed. A general block diagram of an installation for obtaining petawatt-level femtosecond pulses by parametric amplification is presented. The principle of parametric amplification is used not only to obtain ultra-high powers and intensities, but also to achieve high values of other parameters.