K. I. Kisilenko – 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.nnov.ru

G. S. Malyshev – Post-graduate Student,

Department of Physics and Technology of Optical Communication,

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

E. P. Timofeev – Ph.D. (Eng.), Professor,

Department of Physics and Technology of Optical Communication,

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