| 摘要 |
PURPOSE: To provide an optical fiber amplifier which facilitates the feedback control of its amplification factor while the wavelength of an exciting light supplied to an amplification optical fiber is stabilized under the excitation conditions which provide a high amplification efficiency. CONSTITUTION: An amplification optical fiber 11, an optical wave synthesizing coupler 12, an isolator 13 and an optical branching coupler 14 are successively connected between transmission optical fibers 10 and 15. The intensity of the partial branched light of an output light is detected by a photodiode PD and outputted by a resistor 9 in the form of a voltage Vm . A reference laser beam which has a predetermined wavelength and light intensity is emitted steadily to a travelling-wave semiconductor optical amplifier 16 by a semiconductor laser 17 to which a power is supplied by a power supply circuit 18. The fluctuation of the voltage Vm is detected by an automatic light output controller APC in accordance with a reference voltage Vref and a driving current ID which is to make the fluctuation zero is directly supplied to the traveling-wave semiconductor optical amplifier 16. The travelling-wave semiconductor optical amplifier 16 controls the intensity of the exciting light supplied to the amplification optical fiber 11 by changing the amplification factor or the light reduction factor of the reference laser beam in accordance with the driving current ID. |
