Simulation of the dynamics of heat accumulation during in-volume modification with ultrashort laser pulses

Working with ultrashort pulsed (USP) laser systems with high repetition rates > 100 kHz, heat accumulation effects evolve and subsequently the absorption becomes linear. As a consequence, the process dynamics change significantly. Structuring glasses with those USP Lasers leads to melted lines that are used for waveguides, welding or selective laser-induced etching whose resulting qualities are strongly depending of the structuring results and given smoothness. We perform simulations during in-volume modification processes, by recalculating the absorption behavior in between the iteration steps of heat accumulation. The simulation results provide explanations for smoothness or non-smoothness of modifications comparable to experiments in glass.