| 摘要 |
<p>A control system for an optical element such as an optical amplifier in an optical transmission system comprises means 6 for determining the transmitted optical signal power in each of a plurality of different optical wavelength bands, means 7 for determining which of the powers is closest to a threshold, and means 8 for controlling an output power of the element, or for controlling a parameter which affects the threshold, on the basis of the power closest to the threshold. Since there is no longer any need to allow a margin for possible gain variations between different wavelengths, power output can be controlled with reduced upper or lower margins, and thus error rates reduced, or transmission distances increased. <IMAGE></p> |
