Patent ID: 8861965

Claim:
An optical transmission apparatus comprising: an input receiving a first optical signal from an external device via a transmission line; a transmitter to output a second optical signal to be transferred to other optical transmission apparatus; a first dummy light source to generate first dummy light having a wavelength which is not included in the first optical signal; a first wavelength-multiplexer to wavelength-multiplex the first optical signal received from the external device, the second optical signal output from the transmitter, and an optical signal with a wavelength of the first dummy light, which is not included in the first optical signal and in the second optical signal; a second wavelength-multiplexer to wavelength-multiplex an optical signal with a wavelength, of the first dummy light; and a coupler to multiplex the first dummy light output from the second wavelength-multiplexer and the first optical signal; and an optical amplifier to amplify an optical signal multiplexed by the first wavelength-multiplexer and output the amplified signal to the transmission line, the amplified signal including at least the optical signal with the wavelength of the first dummy light, wherein the first wavelength-multiplexer wavelength-multiplexes an optical signal multiplexed by the coupler and the second optical signal.