Study On The Scattering Properties In System Of Surface Plasmonic Waveguide End-coupled To Cavities

Surface plasmon polaritons are considered to be ideal carriers for quantum information,and have the advantages of overcome diffraction limit,manipulate light on sub-wavelength scales and easy integration,which provides possibility of the integration and miniaturization in photonic devices.In this thesis,quantum and classical methods are used to study the dual-band unidirectional reflectionlessness phenomenon at the exceptional point in the system based on the surface plasmonic waveguide coupling to cavities.The transmission characteristics of the non-Hermitian quantum system based on the surface plasmonic waveguide end-coupled to cavities are investigated.The transmission and reflection amplitudes of SPPs are obtained by solving the eigen-equation of the system.For the same frequency cavity coupling to surface plasmonic waveguide system,two distinct reflection(transmission)peaks appear at wavelength-s of 1513 nm and 1589 nm.The results show that as increasing the coupling strength of the waveguide and the cavity,the resonant peaks gradually widen;as the cavity loss increases,the peak value of the reflection peak decreases while the transmission peak increases significantly,and as the coupling coefficient between the two cavities increases,the distance between two reflection(transmission)peaks becomes wider.For the different frequency cavity coupling to surface plasmonic waveguide system,the dual-band unidirectional reflectionlessness occur at exceptional points(at wave-lengths of 1446 nm and 1556 nm).The dual-band unidirectional reflectionlessness is achieved over a wide waveguide-cavity ratio range,a wide cavities coupling strength range,and a large cavity loss condition.The dual-band unidirectional reflectionlessness is investigated based on metal-dielectric-metal waveguide end-coupled to two nanohole resonators.The results show that dual-band unidirectional reflectionlessness is realized at exceptional points(at frequencies of 205.20 THz and 194.56 THz),and the simulation results are well consistent with the analysis results.In addition,the dual-band unidirectional reflec-tionlessness in antisymmetric(symmetric)mode is insensitive to distance s between two resonators(radius r)and that in symmetric(antisymmetric)mode is blue(red)-shifted with increasing the distance s(radius r).We designed the non-Hermitian quantum system based on the surface plasmonic waveguide end-coupled to cavities,which requires only two resonators to realize dual-band unidirectional reflectionlessness and with high quality factors.Our structures have potential applications in quantum information processing and design surface plasmonic devices.