A.M. Bobreshov - Dr. Sc. (Phys.-Math.), Professor, Department of Electronics, Dean of Faculty of Physics, Voronezh State University E-mail: bobreshov@phys.vsu.ru S.E. Neskorodov - Post-graduate Student, Voronezh State University E-mail: neskorodov93@mail.ru G.K. Uskov - Dr. Sc. (Phys.-Math.), Associate Professor, Department of Electronics, Faculty of Physics, Voronezh State University E-mail: uskov@phys.vsu.ru