Patent ID: 7145717
Filing Date: 2006-12-05
Classification: H01S,H04B

Abstract:
1. An optical amplifier for amplifying an optical signal, the amplifier comprising: an optical amplification section including an amplification medium doped with an active substance for optical amplification and an excitation light source which emits excitation light that is provided to the amplification medium so that optical amplification occurs in the amplification medium; and a constant-gain control section finding out target excitation light power to be set according to a change in the level of an input optical signal on the basis of a correlation between a gain and excitation light power to obtain a target gain, finding out a target drive signal for making the excitation light source emit the target excitation light power on the basis of a correlation function between a drive signal for driving the excitation light source and excitation light power, and exercising constant-gain control over the optical amplification section by a feedforward control system, wherein the constant-gain control section generates the correlation function according to a change in characteristics of the excitation light source which changes due to degradation over time, between a drive signal and excitation light power by varying the drive signal and by regularly measuring excitation light power, and finds out a target drive signal from the target excitation light power on the basis of the correlation function.