  We consider the asymmetric active coupler (AAC) consisting of two coupled
dissimilar waveguides with gain and loss. We show that under generic
conditions, not restricted by parity-time symmetry, there exist finite-power,
constant-intensity nonlinear supermodes (NS), resulting from the balance
between gain, loss, nonlinearity, coupling and dissimilarity. The system is
shown to possess nonreciprocal dynamics enabling directed power transport and
optical isolation functionality.
