Optical transmission device and system

摘要

An oscillator 102 outputs an additional signal with a frequency which is higher than a frequency corresponding to a bandwidth of a frequency band allotted to an electrical signal to be transmitted and lower than a half of a lowest frequency of a frequency band allotted to the electrical signal to be transmitted. Thereby, if a second order intermodulation distortion between the additional signal and the electrical signal to be transmitted occurs, a frequency where distortion occurs is outside the all frequency bands allotted to the electrical signal to be transmitted, and the occurring second order intermodulation distortion does not affect the electrical signal to be transmitted. Further, if the second order intermodulation distortion of the additional signal occurs, the frequency where distortion occurs is outside the all frequency band allotted to the electrical signal to be transmitted, and the occurring second order intermodulation distortion does not affect the electrical signal to be transmitted. Not only noise and distortions caused by reflected optical signal but also OBI noise can be reduced by using the additional signal.