Optical isolation via 𝒫 𝒯 -symmetric nonlinear Fano resonances.

We show that Fano resonances created by two 𝒫 𝒯 -symmetric nonlinear micro-resonators coupled to a waveguide, have line-shape and resonance position that depends on the direction of the incident light. We utilize these features in order to induce asymmetric transport, up to 47 dBs, in the optical C-window. Our theoretical proposal requires low input power and does not compromise the power or frequency characteristics of the output signal.