To the question of quantum cryptography transmission system with polarized coding development

There is analysed the existing methods of stability increase for key transmission of quantum cryptographic optical communication system with polarized coding. Also there is estimated the mode dispersion delay for the modern optical fibers, used in communication system range 150-200 km, in comparison to coherency interval of semiconductor lasers, based on GaAs. The recommendations of optic using of optical fibers and lasers for real quantum cryptography systems are given.