Patent ID: 7372622

Claim:
An optical transmission method in an optical transmission system connecting two end offices with an optical transmission line, on which one or more amplifiers, are disposed between an end office and an optical repeater, between two optical repeaters, or between two end offices, and are operable to amplify at least light in a specific wavelength band included in a wavelength-multiplexed light propagating through the transmission line, said optical transmission method comprising: amplifying at least light in a short wavelength band included in wavelength-multiplexed light using first amplifiers including each an excitation light source; and amplifying said short wavelength band and a long wavelength band including wavelengths in the wavelength-multiplexed light which are longer than wavelengths in said short wavelength band, using second amplifiers, and providing a first interval along the optical transmission line between said first amplifiers is shorter than a second interval along the optical transmission line between said second amplifiers, wherein said second amplifiers amplify said short wavelength band and said long wavelength band such that a light intensity difference between light in said long wavelength band and light in said short wavelength band is reduced, and light intensities of said short wavelength band and said long wavelength band are the same when the multiplexed light exits said transmission line.