Nonlinear absorption dynamics simulated in internal modification of glass at 532nm and 1064nm by ultrashort laser pulses

摘要： Dynamic ionization process at high pulse repetition rate is analysed based on the model consisting of rate equation for free-electrons, Gaussian beam propagation equation, thermal conduction and thermal ionization, showing the plasma generated near the geometrical focus moves toward the laser source periodically by the contribution of avalanche ionization. The effects of laser wavelength on the ionization process are discussed by comparing the contributions of multiphoton ionization and avalanche ionization. The crack tendency of 532nm and 1064nm is also compared between single pulse and multipulse irradiation.