Tunable nonreciprocal reflection and its stability in a non-PT-symmetric plasmonic resonators coupled waveguide systems

We investigated optical responses in a non-PT-symmetric plasmonic resonator coupled waveguide by using developed coupled mode theory and the finite-difference time-domain simulation. A nonreciprocal reflection (NR) can be achieved by tuning the direct coupling and the dissipation, which can be used to design nonreciprocal optical devices. The results show that the direct coupling can reduce the nonreciprocal degree of reflection, and especially, greatly discrepant dissipation in the two resonators can give rise to obvious NR. Moreover, the simulation results are in good agreement with the theoretical results. These results will pave a way for realization of stable nonreciprocal devices.