Research Of Unidirectionl Reflectionless Property In Non-hermitian Suface Plasmonic Waveguide Systems

Surface plasmon polaritons(SPPs)is an electromagnetic mode that free elec-trons on the metal surface couple with photons.The charges on the metal surface appear resonance with collective oscillation when the resonant frequency of free elec-trons is same with the photons.Because of the prominent features that SPPs can overcome the limit of traditional optical diffraction and manipulate optical wave on sub-wavelength scales,it has been considered to be information carriers in highly integrated optical circuits.Based on numerical simulation and analytical calcula-tion,we researched single-and dual-band unidirectional reflectionlessnesses in the non-Hermitian suface plasmonic waveguide systems.The main research content is as follows:(1)Based on far field phase coupling between two suface plasmonic resonators,single-band unidirectional reflectionless propagation is theoretically investigated.By observing the z-component distributions of magnetic field,the low reflection occurs duo to the Fabry-Perot(FP)resonance coupling when the phase difference between two resonators is closed to 27r.(2)Single-band unidirectional reflectionless phenomenon is researched based on near field phase coupling between two suface plasmonic resonators.From the distributions of component magnetic field,we find that by reason of the destruc-tive interference the low reflection appears when the phase difference between two resonators is closed to π.(3)Dual-band unidirectional reflectionlessness are studied based on near-field coupling between a single resonator and the resonant modes of two resonators show-ing an electromagnetically induced-transparency-like(EIT-like)effect.When the antisymmetric and symmetric modes of two coupled resonators respectively form the phase difference 7r with the single resonator,the low reflection occurs.Comparing with other unidirectional reflectionless structures,our suface plasmonic waveguide systems are not doped by gain or loss media and do not demand that one of the resonators has a smaller width compared to the other one,hence they are not only more compact but also much easier to fabricate through experiments.