  PT-symmetric optical resonators combine absorbing regions with active,
amplifying regions. The latter are the source of radiation generated via
spontaneous and stimulated emission, which embodies quantum noise and can
result in lasing. We calculate the frequency-resolved output radiation
intensity of such systems and relate it to a suitable measure of excess noise
and mode nonorthogonality. The lineshape differs depending on whether the
emission lines are isolated (as for weakly amplifying, almost hermitian
systems) or overlapping (as for the almost degenerate resonances in the
vicinity of exceptional points associated to spontaneous PT-symmetry breaking).
The calculations are carried out in the scattering input-output formalism, and
are illustrated for a quasi one-dimensional resonator set-up. In our
derivations we also allow for the more general case of a resonator in which the
amplifying and absorbing regions are not related by symmetry.
