The effects of dispersion on optical fiber chaotic secure communication

摘要

The effects of dispersion on optical fiber chaotic secure communication are numerically investigated. A theoretical model for fiber chaotic secure communication system which is consisted of a pair of synchronized chaotic lasers and an optical fiber channel is presented. Chaotic secure communication for a 1-GHz sinusoidal message after propagating several hundred kilometers is numerically analyzed. By numerically studying the effects of dispersion on the system's performance, we show that the synchronization progressively degrades and the signal-to-noise ratio of the recovered message decreases as the fiber length increases. We also find that the signal-to-noise ratio descends when the modulation frequency of the encoding message increases. We propose a dispersion management scheme to compensate the dispersion in fiber chaotic secure communication system. The proposed dispersion management map is consisted of a segment of 5-km dispersion-compensating fiber with value of dispersion β_2=-49ps~2/km, a segment of 245-km nonzero dispersion-shifted fiber with value of dispersion β_2=lps~2/km and optical amplifiers. The results show that the signal-to-noise ratio of the extracted 1-GHz sinusoidal message increases from 2.75dB to 14.02dB when the length of fiber is set to 500km.