Graduate Research and Discovery Symposium (GRADS)


Dr. Xin Zhao, Assistant Professor

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Femtosecond laser interaction with fused silica has been experimentally investigated with wide range of repetition rate (10 Hz-10 kHz) to study the impact on ablation at various laser pulse energy and pulse number. Incubation effect can reduce the ablation threshold by more than half of that at single-pulse irradiation, and increase the ablation rate by over 50% with up to 100 laser pulses. Thermal accumulation effect can be negligible with repetition rate lower than 1 kHz for fused silica, and helps to enhance the ablation rate at 10 kHz (100 pulses) to almost double of that with single pulse. Plasma defocusing effect by air ionization can be observed at pulse energy over 200 μJ, and the reduction of peak fluence can be corroborated by the decrease of ablation rate. Numerical simulation based on combination of plasma model and two-temperature model helps to demonstrate aforementioned dominating mechanisms during interaction between ultrafast laser and fused silica at single-pulse and multi-pulse modes.