{HEAD ~ A proportionate signal} may be split off from each channel and taken to a photodetector to enable {TAIL ~ the gain} of the associated SOAs to be adjusted to equalize or otherwise balance the signal levels 
{ HEAD ~ A proportionate signal } may be split off from each channel and taken to a photodetector to enable { TAIL ~ the gain } of the associated SOAs to be adjusted to equalize or otherwise balance the signal levels
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