| 摘要 |
An optical fiber and an optical amplifier, in particular for optical fiber telecommunication lines operating with a transmission signal in a predetermined wavelength range. The amplifier comprises laser emitting active optical fiber doped with erbium and a further doping substance, distributed along the fiber. The further doping substance has an absorption for a light having a wavelength lower than 1,540 nm substantially higher than the absorption that the further doping substance shows for a light having a wavelength varying from 1,540 nm to the upper limit of the predetermined wavelength range of the transmission signal. Preferably, the further doping substance is samarium. Samarium contained in the fiber is capable of absorbing the spontaneous erbium emission, which would constitute a noise source, thereby allowing a communication signal to be amplified in a wavelength range corresponding substantially to the tolerance range of the commercially available laser light emitters used as the communication signal source.
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