| 摘要 |
PURPOSE:To provide an optical preamplifier in which a narrow band optical band-pass filter can be employed. CONSTITUTION:An optical band-pass filter 12 for subjecting the output light from an optical fiber amplifier 11 is provided with a filter drive means 13 for altering the inclination angle with respect to an input light. The filter drive means 13 is fed with a DC signal from a voltage generating circuit 20 and an AC signal from an oscillation circuit 18 in order to oscillate the transmittance peak wavelength of the filter 12 within a narrow wavelength range around a predetermined reference wavelength. A timing detection circuit 17 detects a timing of maximum light intensity from light intensity signals monitored by an optoelectric conversion circuit 16. A hold circuit 19 holds a current AC signal being fed from the oscillation circuit 18 to the filter drive mechanism 13. The signal thus held is fed to a voltage generating circuit 20 at a predetermined timing in order to alter the DC signal generated therefrom. |
