Scaling the Wavelength to Optimize Ultrafast Laser Processing of Bandgap Materials

Abstract

The spectral characteristics of ultrashort laser pulses offer unique possibilities to control interactions in space and time as well as the subsequent material responses. In particular, selecting the wavelength predefines the fundamental mechanisms governing laser-matter interaction, and thus, how energy is deposited. This Chapter provides an overview on how the essential physical effects in ultrafast laser-matter interaction scale with the wavelength, and the consequences for bandgap material processing applications. First, we recall the main spectral properties of bandgap materials and discuss the important question of the expected processing resolutions depending on wavelength. Then, recent studies on the impact of the wavelength in ultrafast laser-dielectric interaction are presented. Finally, we present how the latest developments in infrared ultrafast laser sources can be advantageously utilized to internally process narrow-gap materials despite challenges related to increased nonlinearities.