Transmission of Intense Femtosecond Laser Pulses into Dielectrics

Summary form only given. The interaction of intense, femtosecond laser pulses with a dielectric surface is examined using a numerical simulation. The simulation uses the 1D electromagnetic wave equation to model laser pulse propagation. In addition, it includes multi-photon ionization, electron attachment, ohmic heating of free electrons, and temperature dependent collisional ionization. Laser pulses considered in this study are characterized by peak intensities ~10¹²-10¹⁴ W/cm² and pulse durations ~10-100 fsec. These laser pulses interacting with fused silica are shown to produce above-critical plasma densities and electron energy densities above experimentally measured damage thresholds. Significant transmission of laser energy is observed even in cases where the peak plasma density is above the critical density for reflection. A damage fluence based on absorbed laser energy is calculated for various pulse durations. The calculated damage fluence is found to be consistent with recent experimental results