Patent ID: 8606115

Claim:
An optical transmission apparatus comprising: a demultiplexer into which is input light output from a reception end of a transmission line that propagates main signal light and optical supervisory channel light that is different from the main signal light while Raman amplifying each of the main signal light and the optical supervisory channel light, and that has a predetermined transmission band centered on a wavelength of the optical supervisory channel light, and that demultiplexes the optical supervisory channel light with noise light generated by Raman amplification in the transmission line from the input light in accordance with the transmission band, and an optical supervisory channel light receiver that receives the optical supervisory channel light that has been demultiplexed by the demultiplexer, wherein there is provided a noise light cutoff section arranged on an optical path between the reception end of the transmission line and the demultiplexer or an optical path between the demultiplexer and the optical supervisory channel light receiver, that passes the main signal light and the optical supervisory channel light, and cuts off noise light included in at least one end portion band on a short wavelength side and a long wavelength side of the transmission band, out of the noise light corresponding to the transmission band of the demultiplexer.