Patent ID: 7725032

Claim:
An optical transmission apparatus with an optical add drop multiplexer (OADM) that adds/drops an optical signal to/from a transmission path, the optical transmission-apparatus comprising: a pump light multiplexer that is located downstream of the OADM on the transmission path; a dispersion compensation fiber that is located downstream of the OADM on the transmission path; an optical amplifier; and a first detector for detecting a total intensity of an optical signal input to the optical amplifier, the optical signal including short-wavelength signals, medium-wavelength signals, and long-wavelength signals, wherein the optical transmission apparatus is configured to house a pump light source connectable to the pump light multiplexer to Raman amplify an optical signal in the dispersion compensation fiber; a second detector that detects an intensity of the short-wavelength signals; a third detector that detects an intensity of the long-wavelength signals; and a controller that calculates an intensity of the medium-wavelength signals based on the total intensity, the intensity of the short-wavelength signals, and the intensity of the long-wavelength signals, and that controls the pump light source to maintain the total intensity of the optical signal and wavelength characteristics of the optical signal.