OPTICAL AMPLIFIER

摘要

An optical amplifier having a series of optical fibers to which a rare earth element is added comprises one or more variable light-attenuating means and attenuation control means for varying the light attenuation of the variable light-attenuating means according to the temperature of the optical fibers or of the environment. An optical amplifier, in another aspect, having a series of optical fibers to which a rare earth element is added comprises a replaceable optical part, one or more variable light-attenuating means, and attenuation control means for varying the light attenuation of the variable light-attenuating means according to the temperature of the optical fibers or of the environment. An optical amplifier, in further another aspect, having a series of optical fibers to which a rare earth element is added comprises one or more externally-controllable variable light-attenuating means the light attenuation by which is changed with the intensities of the input and output signal lights of the optical amplifier.