Patent ID: 6930823

Claim:
An optical transmission method, using Raman amplification to amplify a wavelength division multiplexed signal light including a plurality of optical signals of different wavelengths transmitted among a plurality of optical transmission apparatuses and supplying a pumping light to a Raman amplification medium existing on an optical transmission path so as to Raman amplify the wavelength division multiplexed signal light propogating through the Raman amplification medium, wherein a supervisory signal transferred among said plurality of optical transmission apparatuses is selectively superimposed on the pumping light supplied to said Raman amplification medium, and wherein when a plurality (m) of pumping lights of different wavelengths are supplied to said Raman amplification medium, and said supervisory signal is selectively superimposed on at least one of 1 through (m−1) of said plurality of pumping lights of different wavelengths.