| 摘要 |
PURPOSE: To make constant the wavelength dependency of the gain over a wide range of intensity of input light by suppressing variation in the wavelength dependency of the gain due to variation in the intensity of input light. CONSTITUTION: Total quantity of element or ion being amplified at first optical amplifier sections 14, 16, 18 is low and it is excited with excessive first exciting light thus amplifying an input signal light. Total quantity of element or ion being amplified at second optical amplifying sections 28, 30, 32 is high as compared with the first optical amplifying sections and it is excited with a second exciting light of constant intensity thus amplifying the signal light outputted from the first optical amplifying sections. First control sections 21, 22, 24 control the intensity of output signal light from the first optical amplifying sections to a constant level. |
