| 摘要 |
PURPOSE: An optical fiber amplifier for gain flattering is provided to enable amplifying gains with respect to each signal to be graded without restricting level of signal having high gain by using a filter. CONSTITUTION: A control circuit(8) drives and controls a laser diode(13) for pumping on the basis of power levels detected by the first and the second photo diodes(7,11) and thereby producing pumping light(P) for optical amplification. The pumping light(P) outputted from the laser diode(13) is divided into as a predetermined ratio by a dividing coupler(14). The divided pumping lights are applied to a first wavelength dividing coupler(6) mounted at an input terminal of the first optical amplifying unit(21) and to the second wavelength dividing coupler(16) mounted at an input terminal of the second optical amplifying unit(22). A filter(15) removes gain as to the amplified signal having wavelength of 1530 nm to 1540 nm.
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