| 摘要 |
PROBLEM TO BE SOLVED: To improve the signal-noise ratio in the light amplification of a wavelength multiplexed signal light. SOLUTION: In addition to a light amplification part 10 which amplifies a wavelength multiplexed signal light and outputs the amplified light from an output terminal, a light removing part, with which the naturally emitted light emitted between the wavelengths contained in amplified wavelength multiplexed signal light is removed, is provided on the latter stage of the light amplifying part 10. At this point, the first boat is connected to the output terminal as a light removing part, the amplified wavelength multiplexed signal light, to be inputted from the first boat, is outputted to the second boat, and the light removing part is connected to the second boat. A light circulator, which outputs the amplified wavelength multiplexed signal light, where a naturally emitted light is removed by the light removing part, is arranged, the signal light of one wavelength, corresponding to each wavelength of the signal light contained in the wavelength multiplexed signal light, is reflected, and the fiber grating, where the light other than the above-mentioned wavelength is passed, is series connected to the second boat in the multiple number of the wavelength multiplexed signal light. |
