Sub-micron patterning of solid materials with ultraviolet femtosecond pulses

The treatment of solid materials using subpicosecond laser pulses at 248 nm is studied. The potential of the combination of femtosecond pulse durations with ultraviolet wavelengths for precise material processing is demonstrated. Imaging techniques combined with diffractive optical elements are exploited for the fabrication of nanometer-scale features on practically all classes of materials including metals, semiconductors, and dielectrics. Two-dimensional periodic surface structures with excellent quality and reproducibility over large areas with feature sizes down to the 100 nm range are reached . An extension of this technique to transparent solids to reach defect sizes of a few hundreds of nanometers inside various materials is also possible. As a technical highlight, efficient drilling of a great number of holes with diameters below 500 nm through metal foils is demonstrated. Irradiation is performed using a UV laser system based on a Ti:Sapphire-Excimer hybrid device generating 300 fs pulses at 248 nm. Operation at 300 Hz (resulting in 10 W average output power) allows high speed machining, opening up new possibilities in industrial applications.