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