1. Ivan Franko National University of Lviv, Vlokh Institute of Physical Optics, 23 Dragomanov Str., 79-005 Lviv, Ukraine
2. University of Zielona Góra, Institute of Physics, 4a Szafrana Str., 65-516 Zielona Góra, Poland
3. University of Rzeszów, Institute of Materials Engineering, 16a Rejtana Str., 35-310 Rzeszów, Poland