  A system of two coupled semiconductor-based resonators is studied when lasing
around an exceptional point. We show that the presence of nonlinear saturation
effects can have important ramifications on the transition behavior of this
system. In sharp contrast with linear PT-symmetric configurations, nonlinear
processes are capable of reversing the order in which the symmetry breaking
occurs. Yet, even in the nonlinear regime, the resulting non-Hermitian states
still retain the structural form of the corresponding linear eigenvectors
expected above and below the phase transition point. The conclusions of our
analysis are in agreement with experimental data.
