  A discrete-time two-user interference channel model is developed that
captures non-linear phenomena that arise in optical fiber communication
employing wavelength-division multiplexing (WDM). The effect of non-linearity
is that an amplitude variation on one carrier induces a phase variation on the
other carrier. Moreover, the model captures the effect of group velocity
mismatch that introduces memory in the channel. It is shown that both users can
achieve the maximum pre-log factor of 1 simultaneously by using an interference
focusing technique introduced in an earlier work.
