Femtosecond laser ionization and damage mechanisms in transparent materials

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This project focuses on studying plasma formation and material damage produced by nonlinear absorption of laser pulses in transparent materials. By tightly focusing ultrashort laser pulses, preliminary evidence of material damage with as little as five nanoJoule of laser energy has been observed. Because of the low pulse energy and tight focusing used in the experiments, intensities producing permanent damage can be achieved with minimal self-focusing, allowing the field intensity at the focus to be accurately determined. Measuring the threshold intensity for various laser and material parameters affords the group an opportunity to identify the relative role of multiphoton, tunneling, and avalanche ionization processes in femtosecond laser interactions with bulk media. In addition, detailed studies of the damage morphology for different laser parameters will uncover the basic damage mechanisms at work and provide useful information for applications.