Patent ID: 8554070

Claim:
An optical transmission apparatus comprising: a storage device which stores information regarding a channel from which an optical transmission apparatus at a subsequent stage drops a signal light; and a processor that is operative to determine that switching from second channel transmission, using a larger number of channels than a first number of channels, to a first channel transmission has been performed, and to control an attenuation amount, at the time of performing the first channel transmission using the first number of channels, so as to transmit an amplified spontaneous emission light along a no-signal channel a wavelength which is within a determined range from a wavelength of a signal light channel, and to refer to the storage device according to the determination and make, in the case of the no-signal channel, the wavelength which is within the determined range from the wavelength of the signal light channel, and used in the first channel transmission being the channel from which the optical transmission apparatus at the subsequent stage drops a signal light, an attenuation amount in the no-signal channel larger than a determined value.