S. A. Kapustin – Post-graduate Student,

Department of Physics and Technology of Optical Communication,

Nizhny Novgorod State Technical University n.a. R.E. Alekseev

E-mail: physics@nntu.ru

S. B. Raevskij – Dr.Sc. (Eng.), Professor,

Department of Physics and Technology of Optical Communication,

Nizhny Novgorod State Technical University n.a. R.E. Alekseev

L. G. Rudoyasova – Ph.D. (Eng.), Associate Professor,

Department of Physics and Technology of Optical Communication,

Nizhny Novgorod State Technical University n.a. R.E. Alekseev