Ultra-Precise Materials Processing

Femtosecond lasers (fs-lasers) are the key to ultra-precision processing. Whether in medicine, electronics, aerospace or solar technology, thin coatings can be removed, fiber-reinforced plastics drilled and ceramic components' surfaces structured using fs-lasers.

Wider use of fs-lasers, however, is hampered by the average output which is currently limited to below 100 W on commercial systems. The new fs-laser of the Fraunhofer ILT has an output of over 400 watts and pulse durations of less than 1 ps.

This was made possible by reinterpreting the InnoSlab technology which has been under development at the Fraunhofer ILT for more than 10 years. This technology already forms the basis for numerous nano- and picosecond laser systems in industrial use.

In addition, a reduction and adaptation of the intensities arising is concept-inherent and makes it possible to reach pulse energies below one millijoule - which are relevant in particular for micro materials processing - without the need for complex chirped pulse amplification (CPA). This represents a further breakthrough for the simplification of fs-laser systems and the costs they entail, which is a key requirement for their widespread use in industrial practice.

The innovative laser from the Fraunhofer ILT is characterized by the fact that the oscillators with an output power of 1-2 watts can be amplified up to 400 watts by means of a single amplifier stage.

Further highlights include pulse durations below 700 fs and spectral bandwidths below 2 nm. The pulses are therefore distinctly shorter than on present ps-lasers and produce better results, for example in micro materials processing. Also, the bandwidth and wavelength unrestrictedly permit the use of the same optics as on typical ps and ns lasers. Special attachments for time compression (compressors), as frequently necessary on ultra-short-pulse lasers, are no longer required. The problems which can be caused by these attachments, such as pulse front / phase front tilt, therefore do not arise.

According to all the theoretical and experimental findings, the practical limits of the ultra-short-pulse laser have not yet been reached. The Fraunhofer ILT is therefore already working on scaling the innovative fs-laser to outputs of greater than 1000 watts.

COMPAMED.de; Source: Fraunhofer Institute