Nonlinear susceptibility in crystals induced by femtosecond laser radiation

Abstract

Concentration of band electrons and holes induced by multiphoton ionization in the filament of a femtosecond laser pulse with a diameter of 10 µm before and near the Gaussian waist in nonlinear crystals corresponds to 1018 − 1021 cm−3. Such level of the induced electron-hole polarization component makes an additional contribution to increasing the harmonic generation efficiency in the interaction of femtosecond radiation with nonlinear crystals.