Patent ID: 7660530

Claim:
An optical transmission apparatus for transmitting a wavelength division multiplexed optical signal, comprising: a transmitting unit for transmitting an optical signal with a specified wavelength; a multiplexing unit for multiplexing the optical signal with the specified wavelength and an optical signal with a wavelength other than the specified wavelength and outputting the multiplexed signal as a wavelength division multiplexed optical signal; an optical amplifier for amplifying the wavelength division multiplexed optical signal outputted from the multiplexing unit; a level detecting unit detecting a variation of an optical power of the wavelength division multiplexed optical signal inputted to the optical amplifier; and a level adjusting unit for adjusting, when a variation of the optical power of the wavelength division multiplexed optical signal is detected by the level detecting unit, a transmitting power of the optical signal with the specified wavelength transmitted from the transmitting unit so that an output power becomes a level before the variation, wherein the level adjusting unit includes a level adjuster for adjusting the transmitting power of the optical signal with the specified wavelength which is transmitted from the transmitting unit, and a control circuit for controlling the level adjuster according to the variation of the output power which is detected by the level detecting unit; a through level adjusting unit for adjusting the powers of the optical signals with the respective wavelengths which are caused to pass through the demultiplexing unit and the multiplexing unit; an optical amplifier for amplifying the wavelength division multiplexed signal that is multiplexed by the multiplexing unit; and a wavelength level detecting unit for detecting the powers of the optical signals with the respective wavelengths of the wavelength division multiplexed optical signal which is amplified by the optical amplifier, wherein the through level adjusting unit adjusts the powers of the through optical signals with the respective wavelengths which are caused to pass through the demultiplexing unit and the multiplexing unit to be kept constant on the basis of the powers of the optical signals with the respective wavelengths which are detected by the wavelength level detecting unit.