In-situ observation of ultrashort pulse deep drilling in silicon at 1030 nm and 515 nm

Ultrashort pulse laser micromachining offers exceptional precision and quality for surface treatment as well as structuring with high aspect ratios. While the influence of process parameters like pulse duration, fluence and wavelength is well investigated at the surface of typical materials like metals, studies of the structure in the depth of the material are hindered in non-transparent workpieces. We developed a trans-illumination setup for the direct observation of the drilling process inside silicon, which is used as a model system for materials, which are opaque for the processing radiation. Since the use of frequency-doubled radiation can enhance the process efficiency, we investigate here the details of the deep drilling process at both wavelengths.