Transmission capacity expanding method and optical transmission terminal

摘要

A method to expand a transmission capacity in a WDM optical transmission system including a first optical transmission unit to output to an optical transmission line a plurality of existing signal lights having existing wavelengths different from each other. The method comprises steps of providing a second optical transmission unit to output a plurality of additional signal lights having additional wavelengths different from each other and the existing wavelengths at an error correction ability higher than that of the existing signal lights, and controlling at least one of optical powers of the additional signal light and existing signal light so that the optical power of the additional signal light becomes lower than that of the existing signal light on the optical transmission line.