1. B. I. Stepanov Institute of Physics
2. National Academy of Sciences of Belarus
3. 220072 Minsk
4. Belarus
5. Institute of Physics and Center for Nanostructured Materials and Analytics
6. Technische Universität Chemnitz
7. D-09107 Chemnitz
8. Germany
9. Department of Information Technologies and Robotics
10. National Technical University of Belarus
11. 220013 Minsk