A Variational Signal-Space Distance Measure for Nondispersive Optical Fiber

The nondispersive per-sample channel model for the optical fiber channel is considered. Under some smoothness assumptions, the problem of finding the minimum amount of noise energy that can render two different input points indistinguishable is formulated. The necessary conditions for the noise trajectory that has the minimum energy are described as a system of nonlinear differential equations. It is suggested that this model can be generalized to consider dispersion and to design new communication schemes for fiber-optic communication systems.