Sub-micrometer structuring of metals with femtosecond laser pulses

Summary form only given. During the past years it has been demonstrated that femtosecond lasers are excellent tools for the microstructuring of solid materials. Here we report on our progress in the fabrication of submicrometer structures in 100-200 nm metal-coated surfaces by direct ablative writing with femtosecond laser pulses. Direct ablative writing on the target surface is of great practical importance e.g. for the production and repair of photolithographic masks, optical data storage, etc. We analyze how far one can go in an attempt to reduce the structure size using different laser parameters and optical systems. We identify the best regimes (optimum laser parameters, focusing and/or imaging geometry) for the fabrication of sub-micrometer structures in metal-coated surfaces. We demonstrate that the damage and ablation thresholds depend on the number of pulses which are used to produce a certain structure.