The effect of chirp and wavelength for ultrafast bulk modification of solids with tightly focused laser pulses

Abstract

We report on the clear difference in the behavior of laser-matter interaction of tightly focused high-intensity pulses with the bulk of solids when chirping and tuning the wavelength of the laser driver from near-IR to mid-IR. In transparent dielectrics, laser wavelength scaling leads to the change in the heating mechanism which, in turn, leads to a weak dependence of the plasma formation threshold on the pulse duration in mid-IR (4.6 μm) and a significant impact in the case of the near-IR (1.24 μm) excitation. In the case of semiconductors, the ionization mechanism remains within the framework of the multiphoton approximation, but an increase in the photon order for excitation by mid-IR pulses leads to a decrease in delocalization processes and losses in the prefocal region.