| 摘要 |
<p>The system generates optical signals of different wavelengths (37 to 40), and includes an optical fibre-line with amplifier (45), a preamplifier (47) and a receiver (54 to 57). The preamplifier includes an optical waveguide (5, 7 and 9) doped with a rare earth material. A differential attenuator (8) is located along the waveguide and attenuates in the signal band greater than at the pumping wavelength. A filter (6) is located on the waveguide at a second position and attenuates by a value higher than a preset minimum, the spontaneous emission in a wavelength band contiguous with the signal band. The position and attenuation of the differential attenuator, filter and wavelength band are selected in a functional relationship w.r.t. each other to limit the output power variations from the preamplifier.</p> |
