Abstract

Volumetric modification of transparent materials by femtosecond laser pulses is used for a wide range of applications. In this work, on the example of fused silica, it is shown experimentally and theoretically that in a certain range of energies the peak of absorption of laser radiation for doughnut-shaped pulses is several times larger than for Gaussian pulses. The experiments were performed with 1^st and 2^nd harmonics of the Astrella laser from Coherent. The effect of two different wavelength has also been investigated for single- to multiple-shot irradiation. We show that, due to radiation shielding by laser-generated free-electron plasma, the longer wavelengths are more advantageous for obtaining a more localized modification. This becomes very attractive for the purposes of material modification and laser writing processes.

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