In recent years, optical fiber communication system has made a great development, but the quality of the optical signal will be seriously deteriorated by some factors, such as amplified spontaneous emission (ASE) noise, group velocity dispersion and so on. The traditional regeneration technology is accomplished within the electrical domain, and the opticalelectrical-optical conversion consumes vast amounts of energy. So it is necessary for all optical regeneration technology. This paper introduces the principle of an all-optical 2R regenerator based on self-phase modulation(SPM) and offset filtering technology. The deteriorated optical signal at 40 Gbit/s has been regenerated by the combination of SPM in highly nonlinear fiber (HNLF) and offset filtering. The factors influencing the regeneration have been analyzed by changing related parameters. It is concluded that by reasonably choosing parameters, we can get the best result of all-optical 2R regeneration.
An external modulation technique for the generation of optical linearly chirped frequency continuous waves is proposed and experimentally demonstrated. The output from a distributed feedback (DFB) laser is modulated by a single sideband (SSB) modulator which is driven by a linearly chirped electrical signal generated by an arbitrary waveform generator (AWG). A high precise linear optical frequency sweep with a tuning range of 2.5GHz is successfully achieved. Due to the good modulation quality of SSB and high stability of AWG, the chirp of the electrical signal can be perfectly modulated onto the optical signal. The linearity of the optical signal is almost consistent with the linearity of the electrical signal. The best linearity of 0.9996 and the lowest jitter rate of 4.76 % are obtained from the experimental measurements which are reported in this paper.