Ultrafast Lasers with Radial and Azimuthal Polarizations for
High-efficiency Micro-machining Applications
Project Start Date
(end date 30.04.2017)
High-precision laser micro-machining has delivered a important impact in daily life, hence its benefits and usefulness can easily be taken for granted. For example in the manufacture of smart phones, i-tablets, etc, high-precision laser micro-machining 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 RAZipol 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 <1 µm) 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 work-piece 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 RAZipol project combines several quite unique features. Its modular 3-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 1st amplification stage and a thin-disk multipass amplifier as final amplification stage. Although the potential range of material processing applications for this laser source is extremely broad, within the project, we will focus on two demonstration applications. The first application will be based on a fast scanner system which facilitates the production of complex structures like a “lab on a chip” on large wafers (8” 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. Hence it is believed that RAZipol will have a great impact on the industrial fabrication since it targets cost-efficient solutions for a broad range of applications as well as fast and high-volume applications.