| 摘要 |
PROBLEM TO BE SOLVED: To reduce the wavelength dependency of a signal gain for WDM transmission while output light power is kept constant through the use of an external power source by controlling oscillation light power so that input light power to a light amplifying medium is set to be constant from the detection result of input signal light power and oscillation light power. SOLUTION: An excitation light power control means 33 for keeping the signal light power of output from a light amplifier, an input signal light power detection means 21 and an oscillation light power detection means 26 are provided. Furthermore, an oscillation light power control means 29 for controlling oscillation light power so that input light power to the light amplifying medium becomes constant from the detection results of the input signal light power detection means 21 and the oscillation light power detection means 26 is provided. The oscillation light power of a wavelength different from input signal light is reduced or increased by quantity corresponding to the increase or reduced quantity of input signal light in an amplifying band, and input light power to the light amplifying medium is set to be constant. Thus, the specification of the wavelength of the amplifying gain can be set constant. |
