Spectrum Broadening of Femtosecond Pulses of a Titanium–Sapphire Laser in the Post-Filament Channel with Varying Radiation Wavelength

Spectrum broadening in the post-filament channel of femtosecond laser pulses with an initial wavelength of 944, 744, and 472 nm is experimentally studied. This effect is numerically simulated; spectral red shift mechanisms are discussed by the example of a comparative analysis of experimental and calculated data. It is intended to use the effect under consideration to form two-frequency pulses and their subsequent transformation to the mid-IR by intrapulse difference frequency generation. An analysis shows that 744 nm is the most promising wavelength for this problem among wavelengths under consideration.