High-power ultra-short pulse laser radiation: New sources as key enablers for emerging applications

Abstract

Ultrafast laser sources with pulse durations in the sub-picosecond regime enable a precise machining of various materials. Pulse durations shorter than the electron phonon-coupling time lead to a low thermal load or even non-thermal ablation processes. Exploiting non-linear absorption processes, the absorption becomes nearly material independent when laser pulses of several microjoule energy and high beam quality are focused on the materials surface. Low pulse energies and intensities well above the vaporization threshold and therefore an eduction of the absorbed energy within the ablation product enables a high-precision cutting, ablation and drilling of, even weakly absorbing materials, multi-component and multi-layer systems. Additional, the focusing of ultrafast laser pulses in the volume of transparent dielectrics allows a localized modification of the bulk material. Specifically, defined refractive index changes in glasses and crystals can be utilized for waveguiding and beam-forming applications. A combined approach of material modification followed by chemical etching provides the possibility to manufacture micro-channels or 3D-micro mechanical parts. The 3D-capability of the in-volume material processing originates from the non-linear absorption of light in the initially transparent material.To achieve high process efficiencies in material processing, laser sources delivering high average power are necessary. High average power is achieved either by high pulse energies and low repetition rates or high pulse repetition rates and moderate pulse energies. The optimum set of parameters is strongly depending on the process, the material and the application. In this paper, we present compact laser sources with a high flexibility in pulse energy and pulse repetition rate and an average power of several hundreds of Watt. Additional, a broad range of applications, from micro- and nanostructuring of various materials to volume processing of dielectrics will be presented.Ultrafast laser sources with pulse durations in the sub-picosecond regime enable a precise machining of various materials. Pulse durations shorter than the electron phonon-coupling time lead to a low thermal load or even non-thermal ablation processes. Exploiting non-linear absorption processes, the absorption becomes nearly material independent when laser pulses of several microjoule energy and high beam quality are focused on the materials surface. Low pulse energies and intensities well above the vaporization threshold and therefore an eduction of the absorbed energy within the ablation product enables a high-precision cutting, ablation and drilling of, even weakly absorbing materials, multi-component and multi-layer systems. Additional, the focusing of ultrafast laser pulses in the volume of transparent dielectrics allows a localized modification of the bulk material. Specifically, defined refractive index changes in glasses and crystals can be utilized for waveguiding and beam-forming applications. A...