| 摘要 |
PURPOSE:To keep the output signal light power of an optical amplification fiber constant by controlling the output of an exciting laser in accordance with the power of only signal light from which noise is removed out of the output of the optical amplification fiber. CONSTITUTION:When an optical signal with 1.55mum wavelength, e.g. is inputted from the forward part of the optical amplification fiber 1 excited by output light outputted from an exciting laser diode(LD) 7 having 1.48mum wavelength, e.g. the optical signal is amplified by induced radiation light from the fiber 1 and the amplified signal is outputted. When the spectrum width of the output signal light is set up to 0.3nm, e.g. its noise component is removed by making the light pass through a wide band filter 3' with 2 to 3nm pass band width and noise-removed signal is outputted through a photocoupler 4. A part of the output is branched and made to pass through a narrow band filter 8, only the signal light is inputted to a signal light monitoring part 5 and converted into a DC signal and the light emitting quantity of the LD 7 is adjusted by a drive control part 6 in accordance with a difference signal between a DC signal level and a prescribed reference level to keep the output signal light power of the fiber 1 at a fixed value. |
