Patent ID: 7206512
Filing Date: 2007-04-17
Classification: H04J

Abstract:
1. A method of controlling an optical wavelength division multiplexing transmission apparatus which is equipped with an optical attenuation section for attenuating individually the power level of each of a plurality of input optical signals of different wavelengths, corresponding to each of the wavelengths, an optical multiplexing section disposed in a stage subsequent to the optical attenuation section, for multiplexing the optical signals of each wavelength which have been attenuated by said optical attenuation section and generating a wavelength division multiplexed optical signal, an optical amplification section for amplifying the wavelength division multiplexed optical signal generated by said optical multiplexing section, and a spectral analysis section for analyzing the spectrum of the wavelength division multiplexed optical signal amplified by said optical amplification section, wherein said method comprises: upon startup of said optical wavelength division multiplexing transmission apparatus, setting initial information including the wavelengths being used and the number of wavelengths being used, setting the amount of optical attenuation corresponding to each wavelength of said optical attenuation section to a maximum value, and setting the operation of said optical amplification section to automatic level control; upon input to an optical signal of a wavelength corresponding to the wavelengths being used set in said initial information into said optical attenuation section, controlling the amount of optical attenuation corresponding to the wavelength of the optical signal being input into said optical attenuation section so that the power level of the optical signals of each wavelength analyzed by said special analysis section is approximately constant, and moreover so that the optical power lever per single wavelength of the wavelength division multiplexed optical signal input into said optical amplification section is of a level which corresponds with the number of wavelengths being used set in said initial information; based on the analysis results from said spectral analysis section, controlling the amount of optical attenuation corresponding to the wavelength of the optical signal being input into said optical attenuation section, so that the level conditions adjusted by said controlling the amount of optical attenuation, are maintained; and upon a variation in the number of wavelengths being input, switching the operation of said optical amplification section from automatic level control to automatic gain control, and individually controlling the amount of optical attenuation corresponding to each wavelength of the optical signal being input into said optical attenuation section so that the power level of the optical signal of each wavelength analyzed by said spectral analysis section is approximately constant, and moreover so that the optical power level per single wavelength of the wavelength division multiplexed optical signal input into said optical amplification section is of a level which corresponds with the varied number of wavelengths.