| 摘要 |
<p>A Raman optical amplifier has a plurality of pump sources (14,16,18,20,22). The outputs from at least two pump sources are modulated so as to reduce the interaction between the pump source signals in the fiber. By reducing this interaction, the tilt in the effective noise figure is reduced. In one example, the modulation involves providing the pump signals (1423nm,1444nm and 1464nm,1495nm) at different times. In another example, at least two pump sources have orthogonal polarisations which are varied over time, whilst maintaining orthogonality. <IMAGE></p> |
