A dispersion compensator is added before and after the transmission link of the traditional non-return to zero code fiber optic transmission system composed of the laser, the modulator, the transmission link and the receiver in sequence. The prepositional dispersion compensator adjusts the waveform of the NRZ optical signal output from the modulator and broadents it to the quasi-continuous light in order to restrain nonlinear effect. The postpositional dispersion compensator compresses the quasi-continuous light output from the transmission link symmetrically in order to recover the NRZ optical signal within tolerance of dispersino in order to be received by the receiver. The invention is suitable to different kinds of optical fiber to realize super long distance transmission in undersea communication or in land communication. |