Multiuser Capacity Analysis of WDM in Nonlinear Fiber Optics

The capacity region of wavelength division multiplexing in nonlinear fiber optic channels with coherent communication is studied. We show that by optimally using the information from all the channels at the receiver, the loss in the capacity due to the mixing of channels is negligible in the weakly nonlinear regime. On the other hand, with singlechannel detection, capacity saturates as the total interference power becomes comparable to the noise power. Similar results hold for the case of channels with memory. The transmitter can achieve the capacity without knowing the nonlinearity parameters. Some insight is provided on the structure of optimal/suboptimal receivers.