| 摘要 |
PROBLEM TO BE SOLVED: To attain low loss, to reduce the number of parts and to reduce a cost compared with the case using a waveguide as a distributor by specifying the input and output of wavelength independent type optical fiber couplers connected in plural stages. SOLUTION: One input terminal of a two-input/two-output wavelength independent type optical fiber coupler (2×2WIC coupler) is connected to the output terminal of an optical fiber amplifier 1, and one-input/three-output wavelength independent type optical fiber couplers (1×3WIC coupler) 30, 31 are connected to each output terminal of the 2×2WIC coupler 20, respectively. Moreover, 1×3WIC couplers 32-37 are connected to each output terminal of the 1×3WIC couplers 30, 31, and the gain of the optical fiber amplifier 1 is controlled by the output signal of a photodetector 41 provided on one of the output terminals of them. Also, the output terminal of the optical fiber amplifier 2 is connected to the 2×2WIC coupler 20, and the gain of the optical fiber amplifier 2 is controlled by the output signal of a photodetector 42.
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