Optical transmission device, transmission and reception module, optical transmission system, and wavelength dispersion compensation method in optical transmission device

An optical transmission device comprising:

• a variable dispersion compensator to compensate for chromatic dispersion of an optical transmission path transmitting an optical signal and to output the optical signal;
• a branching unit to branch the optical signal output from the variable dispersion compensator onto a first light path and a second light path;
• a reproduction unit to receive the optical signal transmitted on the first light path and to reproduce a first electric signal from the optical signal transmitted on the first light path and;
• a monitor unit, having a higher sensitivity to a variation of the chromatic dispersion than the sensitivity to the variation of the chromatic dispersion of the reproduction unit, to
• receive the optical signal transmitted on the second light path,
• perform a reproducing process to reproduce a second electric signal from the optical signal transmitted on the second light path,
• convert the second electric signal into a digital signal, and
• control a dispersion compensation amount of the variable dispersion compensator when a signal duration period in which the digital signal corresponding to a single signal value of the optical signal is shorter than a prescribed threshold value,
• wherein a range of a residual chromatic dispersion in which the signal duration period is longer than the prescribed threshold value is narrower than a range of the residual chromatic dispersion in which the reproduction unit may reproduce the digital signal.