  We introduce a new type of synthetic saturable absorbers based on quantum
inspired photonic arrays whose linear light transport characteristics can be
derived via bosonic algebra. We demonstrate that the interplay between optical
Kerr nonlinearity, interference effects and non-Hermiticity through radiation
loss leads to a nonlinear optical filtering response with two distinct regimes
of small and large optical transmissions. More interestingly, we show that the
boundary between these two regimes can be very sharp. The threshold optical
intensity that marks this abrupt "phase transition" and its steepness can be
engineered by varying the number of the guiding elements. The practical
feasibility of these structures as well as their potential applications in
laser systems and optical signal processing are also discussed.
