  We study the breaking of reciprocity in non-Hermitian coupled photonic
waveguides by the simultaneous action of the nonlinear effect of saturable
absorption, and the presence of exceptional points. The nonlinear response of
such a system is studied in depth, giving physical insight into the operational
principles and fundamental limitations, while producing analytical and
semi-analytical results for the transmission and nonreciprocal intensity range.
We numerically validate the theoretical results and assess important
performance metrics for the nonreciprocal operation of such a device. This
novel class of passive non-resonant devices can offer on-chip broadband
nonreciprocal operation, making them potentially very important for high-speed
applications.
