Three-color pump of laser-induced plasmas: sum and difference frequency generation

The generation of strong harmonics and sum and difference frequencies using the propagation of three pulses of different wavelengths and polarizations through Ag, Au, Pb, B, and C plasmas is examined. It is demonstrated that the difference frequency mixing is more efficient compared with the sum frequency mixing. At optimal conditions for the laser-plasma interaction, the intensities of the sum and especially the difference components are almost equal to the intensities of neighboring harmonics attributed to the strong 806 nm pump.