Patent ID: 6519080
Filing Date: 2003-02-11
Classification: H01S

Abstract:
Optical transmission system comprising:an optical transmitting unit to transmit optical signals in a transmission wavelength band above 1570 nm, an optical receiving unit to receive said optical signals, an optical fiber link optically coupling said transmitting unit to said receiving unit and adapted to convey said optical signals, and at least an topical amplifying unit coupled along said link and adapted to amplify said optical signals; said optical amplifying unit having an amplification wavelength band including said transmission wavelength band and comprising: an input for the input of said optical signals, an output for the output of said optical signals, at least an erbium-doped active fiber having a first end optically coupled to said input and a second end optically coupled to said output, for the amplification of said optical signals, a pump source for generating a pump radiation adapted to excite erbium, and an optical coupler optically coupling said pump source to said at least an active fibre, wherein said pump source has an emission wavelength greater than 1400 nm and lower than 1470 nm, and said active fiber has a numeric aperture NA between 0.25 and 0.32 , and wherein the fiber has a core wherein Al concentration in the core is between 1% and 6% weight molar concentration.