Controllable Dual-band Unidirectional Reflectionlessness In The Surface Plasmonic Waveguide-quantum Dots Systems

Surface plasmons are electromagnetic modes that propagate along the met-al surface,which are caused by the interaction between incident photons and free electrons localized on the metal surface.It has the strong local field enhancement effect,which can not only limit the transmission of light at nanometer scale,but also break the diffraction limit.It provides the possibility to realize the miniaturization and integration of photonic devices,thus becoming an ideal carrier for quantum information processing.The rapid development of nanotechnology has stimulated researchers’interest in the theory of surface plasmons.At present,surface plasmons are widely used in super-resolution nanolithography,new light sources,highly sen-sitive biological detection,high-density data storage and other fields.This thesis mainly studies the dual-band unidirectional reflectionlessness phenomenon in a non-Hermitian quantum system composed of a surface plasmonic waveguide side coupled to twoΛ-type three-level quantum dots driven by classical fields.The specific con-tents are as follows:Based on the model of quantum dots(Ω₁=0.817×4.535×10¹³rad/s,Ω₂=0)driven by single classical field side coupled to a surface plasmonic waveguide,it is equivalent to the situation where aΛ-type three-level quantum dot and a two-level quantum dot interact with the surface plasmonic waveguide simultaneously.The controlled dual-band unidirectional reflectionlessness is achieved at wavelengths1531.05 nm and 1567.28 nm.And the quality factors for forward and backward directions reach～375.4 and～402.6,respectively.In addition,we confirm that the dual-band unidirectional reflectionlessness can be achieved within a wide range of Rabi frequencyΩ₁,the phaseθbetween the two quantum dots,the dissipationΓof the two quantum dots,and the quantum dot-waveguide coupling strengthη.Based on the model of quantum dots(Ω₁=1.154×2.635×10¹³rad/s,Ω₂=1.676×2.635×10¹³rad/s)driven by two classical fields side coupled to a sur-face plasmonic waveguide,it is equivalent to the situation where twoΛ-type three-level quantum dots interact with the surface plasmonic waveguide simultaneously.The controlled dual-band unidirectional reflectionlessness is achieved at wavelengths1526.69 nm and 1575.27 nm.And the quality factors for forward and backward di-rections reach～615.3 and～723.6,respectively.In addition,we confirm that the dual-band unidirectional reflectionlessness can be achieved within a wide range of Rabi frequency ratioΩ₂/Ω₁,the phaseθbetween the two quantum dots,the dissipa-tionΓ₁of the first quantum dot,and the quantum dot-waveguide coupling strengthη,and the effect is more significant than the first case.Both the single classical driving field system and two classical drivinig fields system proposed in this thesis achieve the dual-band unidirectional reflectionlessness and have high quality factors.The research results will provide certain theoretical reference value for the research and design of surface plasmonic switches,diode-like,transistors,filters and other quantum devices.