Capacity-Achieving Input Distributions in Nondispersive Optical Fibers

This paper investigates the discrete-time per-sample model of the zero-dispersion optical fiber. It is shown that the capacityachieving input distribution is unique, has (continuous) uniform phase and discrete amplitude with a finite number of mass points. The optimality of this multi-ring input holds when the channel is subject to general input cost constraints that include peak power constraint and a joint average and peak power constraint. Zero-dispersion optical fiber, channel capacity.