| 摘要 |
PURPOSE:To realize the fiber type optical amplifier in which an excited light level inputted to an optical fiber formed by doping a medium used to amplify a light is controlled constant. CONSTITUTION:An input signal light from a signal light input terminal 6a is amplified by passing through a rare-earth group doped optical fiber 1 and excited output lights from excitation light sources 2, 3 are synthesized by a photocoupler 4, inputted to the fiber 1 by a photocoupler 5, part of the light is branched and subjected to photoelectric conversion by a light receiving device 9 via a band pass filter 8. Moreover, the current is amplified by a light receiving current amplifier circuit 10, branched by a current branch circuit 12 and outputted to excitation light source output control circuits 15, 16. The excitation light source output control circuits 15, 16 applies negative feedback control to the output of the excitation light sources 2, 3 in response to the output signal of the current branch circuit 12 and an output signal of the light receiving devices 13, 14 so that the excited light level inputted to the optical fiber 1 is constant. |
