Power controlling network element for adding new channels in a controlled manner

A power controlling element 10 for a wavelength division multiplexed (WDM) optical communication system includes generating means 60, 70, 80, 90, 92, 94 for transmitting/emitting optical channels to an erbium doped fibre amplifier (EDFA), and a power detector for detecting a branched portion of the amplifier output and relaying this information to a power control unit 40 which preferably is a field programmable gate array (FPGA). The FPGA acts to maintain the power of channels within predetermined limits. When a new channel is added by one of the generating means, the element increases the output of the new channel in a stepwise incremental manner (see figure 2) to reduce power overshoot or surges. Initially, new channels are added at a level which is insufficient to disrupt existing channels in order to check whether the new channel is tuned correctly.