Ultrafast lasers for high efficiency micromachining applications

Stuttgart, Germany - High-precision laser micromachining has had such a big impact on daily life, its benefits and usefulness can often be taken for granted. For example, in the manufacture of smart phones, tablets, etc, high-precision laser micromachining is essential to produce some of the key features we use in these devices.

In the car industry, it is has been shown that diesel nozzles produced with ultrafast lasers lead to significantly reduced air pollution in comparison to nozzles produced with conventional fabrication techniques. Spinning nozzles used widely in the textile industry are also produced using ultrafast lasers.

The main goal of the EU collaborative project RAZipol (Ultrafast Lasers with Radial and Azimuthal Polarizations for High-efficiency Micro-machining Applications) is to demonstrate laser material processing at unprecedented levels of productivity (leading to drilling process times below 4 s of high aspect ratio 40:1 holes compared to current times of 25 s) and precision material processing (structure dimension below 1 micron) using beams with novel radial and azimuthal polarization.

The challenge is not only to achieve high productivity at moderate levels of precision or highest quality at low speeds, but to reach both targets at the same time. Therefore, an adequate ultrafast laser source with a very high average power and well-adapted beam parameters, including pulse duration, pulse energy, intensity profile, and polarization, is needed. Additionally, the laser beam has to be applied to the workpiece in a well-defined application-specific manner. Finally, advanced processing strategies are required to obtain optimum results at high productivity.

The ultrafast laser source planned for the RAZipol project combines several quite unique features. Its modular three-stage master oscillator power amplifier (MOPA) concept offers a high degree of flexibility to generate a broad range of pulse durations, pulse energies, and repetition rates. The MOPA combines an ultrafast oscillator together with a single crystal fiber as a first amplification stage and a thin-disk multipass amplifier as a final amplification stage.

Although the potential range of material processing applications for this laser source is extremely broad, the project will focus on two demonstration applications. The first application will be based on a fast scanner system that facilitates the production of complex structures like a "lab on a chip" on large wafers (8 in. diameter). For this application, the MOPA system providing up to 500 W average power will be set up for repetition rates in the 20-40 MHz range with pulse duration of approximately 1 ps.

The second application will be trepanning drilling of deep, high aspect holes with tight tolerances. In this case, the MOPA system providing up to 200 W average power will be set up for generating high pulse energies (≤ 1 mJ) at pulse duration of about 5 ps. It is believed that RAZipol will have a great impact on industrial fabrication since it targets cost-efficient solutions for a broad range of applications as well as fast and high-volume applications.

RAZipol has a total cost of $5,900,563; the EU contribution is $4,346,130. The project coordinator is the University of Stuttgart in Germany. Participants are GFH GmbH, Schweisstechnische Lehr- und Versuchsanstalt Slv Mecklenburg-Vorpommern, Class 4 Laser Professionals AG, Fibercryst SAS, Centre National de la Recherche Scientifique, Time-Bandwidth Products, and Next Scan Technology BV.

For further information, contact the administrator at the Instituitfuer Strahlwerkzeuge at the University of Stuttgart or go to Cordis Europa.