| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical amplifier which can easily hold an output signal light level to a fixed target level without depending on a level and a wavelength of input signal light. <P>SOLUTION: A part of input signal light is branched by an optical coupler 51 and is branched into first branch light and second branch light by an optical coupler 52. An optical detector 61 detects power of first branch light, and an optical detector 62 detects power of second branch light. Since the branching ratio of the optical coupler 52 has wavelength dependency in a wavelength band in use, the level and the wavelength of input signal light are monitored according to a detection result by the optical detectors 61 and 62. A control unit 70 sets a target level P<SB>total</SB>of light which is to be outputted from an output end 1b according to the level and the wavelength of input signal light. Power of excitation light supplied from an excitation light source 40 to EDF 10 is controlled so that a whole output light level obtained by an optical detector 63 becomes the target level P<SB>total</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
