| 摘要 |
PURPOSE:To provide the light amplifying repeater, which reduces an input loss, for detecting whether signal light is inputted or not with high sensitivity even when the input of signal light to be made incident is small and for stably performing a light amplifying operation until recovering a normal light amplifying state from a standby state. CONSTITUTION:A light wavelength synthesizing coupler 1, rare earth added optical fiber 2, optical isolator 3, optical filter 4 and excitation light source 12 are functioned as light amplifying means. Optically amplified output light branched from a photocoupler 5 is monitored by a photodetector 6 and a signal light detection/wait control circuit 7 and since a switching control signal is outputted to a switching circuit 10 corresponding to whether the signal light is inputted or not, the connection to an excitation light source driving circuit 11 is switched to an output control circuit 8 or a pulse generating circuit 9. The light amplifying means periodically performs the light amplifying operation corresponding to a pulse signal from the pulse generator 9 at waiting time with no input, performs the normal light amplifying operation due to the output control circuit 8 when the signal light is inputted again, and is automatically recovered from the standby state. |
