key members:

• Prof. Thomas Südmeyer (Thomas.sudmeyer@unine.ch)
• Dr Valentin Wittwer (Valentin.wittwer@unine.ch)

Since autumn 2014, LTF has been equipped with a state-of-the-art Ion Beam Sputtering (IBS) coating machine that will be dedicated to the fabrication of custom optics. The selected “Navigator 1100” IBS Optical Thin-Film Deposition System from Cutting Edge Coatings GmbH (Figure 1) is the most suitable deposition machine for ultrafast applications, enabling the growth of dense dielectric multilayer structures with the lowest losses (sub-ppm range), reduced defect densities, and superior optical quality.

Figure 1: Picture IBS machine

With the project OPTICS (OPTical IBS Coating for Swiss reserach) that has been largely funded by the Swiss National Science Foundation (SNF), we want to establish a Swiss platform at the University of Neuchatel that provides a complete solution for the design, sample preparation, layer deposition, characterization, and laser evaluation of top-quality IBS coatings. With this machine, we will have a unique possibility to use and develop custom optics for all our research fields, i.e., to fabricate optics that are perfectly adapted to the specific needs of our experiments.
A major focus will be for the project “MEGA-XUV”, which is highly demanding in terms of optical components, especially intra-cavity dispersive mirrors, for the generation of high harmonics directly inside the intra-cavity beam of a femtosecond oscillator operating at unprecedented high power levels. Intolerable nonlinearities, thermal effects, and even damage are observed with state-of-the-art commercial mirrors, leading to the need of custom-designed optics.
This infrastructure will also pave the way for many collaborations, where custom-made high-performance coatings are required that exhibit special properties and which are not commercially available. A map of different national and international collaborations that are foreseen using this IBS coating machine is shown in Figure 2. It includes Swiss research institutes, but also a network of Swiss industries
 

Figure 2: Map of the Swiss and international landscape of collaboration to be realized within the OPTICS project.

Dielectric layers deposition using IBS is based on an ion-beam that impinges a target made of the coating material. The ion-beam transfers its momentum to a particle stream of the target material which is deposited on a substrate. Using an ion-beam allows changing independently the ion-flux and the ion-energy. Therefore, it is possible to obtain low-bandwidth ion energy at arbitrary deposition rates. Furthermore, because of the comparably high energy of the ions, the particles of the coating material have a relatively high impact velocity on the substrate.
All these mentioned properties allow to realize state-of-the-art coatings that

• are extremely uniform,
• have a very high-density (possible to be qualified for space),
• are completely amorphous,
• have excellent adhesion properties to the substrate.

Furthermore, this is possible at very high precision and achieves excellent surface roughness.

This new research tool will allow several generations of PhD students and post-graduate researchers to perform cutting-edge research on dielectric multilayer systems that are crucial for launching and accelerating research in numerous ground-breaking directions.