  We investigate the range of validity of the recently developed steady-state
ab-initio laser theory (SALT). While very efficient in describing various
microlasers, SALT is conventionally believed not to be applicable to lasers
featuring fully or nearly degenerate pairs of resonator modes above the lasing
threshold. Here we demonstrate how SALT can indeed be extended to describe such
cases as well, with the effect that we significantly broaden the theory's
scope. In particular, we show how to use SALT in conjunction with a linear
stability analysis to obtain stable single-mode lasing solutions that involve a
degenerate mode pair. Our flexible and efficient approach is tested on
one-dimensional ring lasers as well as on two-dimensional microdisk lasers with
broken symmetry.
