| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical amplifier that can achieve higher S/N characteristics. SOLUTION: Excitation light is multiplied by a directional coupler 22 arranged in front of an optical amplification medium 20 for amplifying a light signal that is optically amplified by the optical amplification medium 20 for amplifying the light signal. Also, in a directional coupler 23 arranged in the rear of the optical amplification medium 20, the excitation light is multiplied to the light signal that is optically amplified by the optical amplification medium 20. Forward and backward excitation light sources 31 and 32 emit the excitation light, and light emission in the forward and backward excitation light sources 31 and 32 is controlled by controlling circuits 40 and 50. An optical amplification section is composed by each of the sections, the output of the forward excitation light sources 31 is set to the allowable maximum value, and a gain control function for compensating for shortage by the backward excitation light source 32 is composed, thus achieving two-way excitation using forward and backward excitation at the same time, securing gain by the forward excitation as much as possible to secure a required S/N ration, and compensating for the shortage by the backward excitation. |
