| 摘要 |
PROBLEM TO BE SOLVED: To keep the level of an optical output with high accuracy by making it clear that a cause of a conventional optical amplifier is unable to keep an optical output level constant and eliminating this problem. SOLUTION: The amplifier device is provided with an optical amplifier 10 that amplifies a signal light with a specific wavelength and outputs an amplified signal light, 1st and 2nd optical branching devices 20, 21 branching part of the amplified signal light to provide respectively an output of the branched signal light, and a band rejection optical filter 40 which eliminates a light in a predetermined wavelength band around the specific wavelength from the branched signal light and passes selectively only a natural emission light only at a pre-stage of the 2nd optical branching device, a subtraction processing circuit 50 sending a control signal in response to the difference between the 1st branched signal light and the natural emission light and an optical amplifier control circuit 51 controlling the output of the amplified signal light based on the control signal. A dielectric multi-layer film optical filter, a fiber grating optical filter or a guide path optical filter is adopted for the band rejection optical filter 40. |
