Mathematical simulation of an experimental prototype of a high-speed nonreturn-to-zero differential phase-shift-keying fibre-optic communication system

The influence of chromatic dispersion, optical power, and nonlinear distortions in a fibre-optic communication system on the quality of data transmission based on nonreturn-to-zero differential phase-shift keying at a rate of 40 Gbit s^-1 in one spectral channel have been numerically simulated and experimental studied. The results of direct numerical calculations and estimates based on the quality factor (Q factor) are in qualitative agreement with the experimental data. It is found experimentally that the dependence of the error rate on the accumulated dispersion has a plateau in the range from —50 to 50 ps nm^-1; a similar dependence is obtained in the numerical calculation based on the Q factor. The optimal calculated value of the power launched into each of 10 sections of a line with a total length of 1000 km is 2 — 4 dBm; it corresponds to the experimental value of 3 dBm.