Abstract

In frequency-division subcarrier-multipiexed (SCM) systems using intensity modulation, although the channel-carrying capacity is large, it is fundamentally limited by the fact that if the product of the number of channels and the modulation-current depth per channel exceeds the laser threshold current, the input current will occasionally drop below the threshold current, turning the laser off.¹ Since the power of each subcarrier channel is proportional to the modulation depth, in an effort to maximize the number of channels transmitted by a single laser, some amount of clipping distortion is usually tolerated.

© 1994 Optical Society of America