Optical transmission system

摘要

It is configured to have a first optical line terminal for transmitting a video signal of a first wavelength; a second optical line terminal for transmitting a downstream data signal of a second wavelength and receiving an upstream data signal of a third wavelength; and a wavelength division multiplexer for wavelength division multiplexing the video signal and the upstream data signal and the descend data signal, where an attenuator is provided between the second optical line terminal and the wavelength division multiplexer, the attenuator having a characteristic that an attenuation amount given to the second wavelength is larger than an attenuation amount given to the third wavelength.