1. B.I. Stepanov Institute of Physics of NAS, 220072 Minsk, Belarus
2. State Scientific and Production Association “Optics, Optoelectronics and Laser Technology” of NAS, 220072 Minsk, Belarus
3. Faculty of Physics and Information Technology, Francisk Skorina Gomel State University, 246028 Gomel, Belarus
4. Belarusian Scientific Research and Design Institute of Oil, 246003 Gomel, Belarus