  We study the competing effects of stimulated and spontaneous emission on the
information capacity of an amplifying disordered waveguide. At the laser
threshold the capacity reaches a "universal" limit, independent of the degree
of disorder. Whether or not this limit is larger or smaller than the capacity
without amplification depends on the disorder, as well as on the input power.
Explicit expressions are obtained for heterodyne detection of coherent states,
and generalized for arbitrary detection scheme.
