SYNCHRONIZATION SIGNAL DISTORTION IN SUBCARRIER WAVE QUANTUM KEY DISTRIBUTION SYSTEMS
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For citation: Dubrovskaia V.D., Chivilikhin S.A. Synchronization signal distortion in subcarrier wave quantum key distribution systems. Scientific and Technical Journal of Information Technologies, Mechanics and Optics, 2017, vol. 17, no. 4, pp. 599–604 (in Russian). doi: 10.17586/2226-1494-2017-17-4-599-604
Subject of Research.The paper deals with temperature effects dependence of the synchronization signal parameters in an optical fiber cable for a subcarrier wave quantum communication system. Two main causes of signal distortion are considered: the change in the refractive index as a function of the average daily temperature and the dispersion effects in the optical fiber, over which the signal is transmitted in the system. Method. To account for these effects, a temperature model has been created. The signal delay is calculated as a result of external influences in the system working with a standard fiber-optic cable. Real operational conditions are taken into account, including cable laying conditions, average daily temperature and wind speed. Main Results. The simulations were carried out on the standard single-mode fiber ITU-T G.652D. It was experimentally obtained that the maximum calculated phase mismatch of the synchronization signal for a system operating at a 100 km fiber length corresponds to a 1.7 ps signal time delay. The maximum operating intervals of the system without the use of phase adjustment are calculated. The obtained results are used to improve the parameters of the subcarrier wave quantum communication system. It is determined that the change in the refractive index in the fiber causes significant distortion of the signal. It is shown that stable operation is possible with adjustment every 158 ms. The additional phase delay resulting from the dispersion effects should be adjusted every 2.3 hours. Practical Relevance. The obtained results enable to optimize the parameters of the subcarrier wave quantum key distribution system to increase the overall key generation rate.
Acknowledgements. The research has been carried out with the financial support of the Government of the Russian Federation (074-U01) and the Ministry of Education and Science of the Russian Federation under grant agreement #14.578.21.0112 (RFMEFI57815X0112) and contract No 02.G25.31.0229.