Surface Plasmon-Based Electromagnetically Induced Absorption Mechanism And Its Application

Surface Plasmons polaritons(SPP)are electromagnetic waves propagating along the metal surface formed by the coupling of free electrons in the metal and electromagnetic fields in the medium.Due to their unique local field enhancement characteristics,the electromagnetic beam can be bound to the sub-wavelength to break through the diffraction limit.Therefore,SPP is widely used in integrated devices such as filters,optical switches,and sensors.In these fields,how to regulate the transmission of SPP in nanostructures according to people's wishes is an important issue,which occupied scholars'attention for a long time.Realizing the dynamic regulation of SPP on optical integrated devices has become a research hotspot in recent years.Plasmon induced transparency effect,which is a plasmonic analog to the electromagnetic induced transparency,has attracted a great deal of attention due to its abnormal dispersion and momentous applications.Compared to the plasmon induced transparency effect,the plasmon induced absorption(PIA)effect also arises from the constructive interference of the bright and dark mode,leading to a sharp dip within a relatively broad transmittance peak.It possesses abnormal dispersion,unique fast-light features,a narrow line-width accompanied with the enhanced absorbance,and many applications including optical modulator,optical switching,absorber,sensor,fast light and so on.However,there are few studies on the dynamic regulation of the PIA effect,especially the theoretical research and application of multiple PIA effects.This paper focuses on two different structures,namely metal-dielectric-metal(MIM)waveguide coupled resonator and graphene nanoribbon waveguide system,to study the theory of multi-PIA effect and its dynamic adjustability in logic gates and sensors.The main research points of this paper are as follows:1.In the metal-dielectric-metal(MIM)waveguide coupled resonator structure,we introduce the light-dark-dark couple mode into the traditional coupled mode theory(CMT)to derive the coupled mode theory of multiple PIA effects.Numerical simulation results show that the theory has high accuracy and universality.Then the time domain finite difference method(FDTD)is used to analyze the electromagnetic field distribution in the coupling cavities,and the mechanism of multi-PIA effects is explained by the constructive interference between the direct and indirect coupling paths.In addition to studying the regulation mechanism of statically adjustable structural parameters on PIA effect,we attempt to fill the coupling cavities with Kerr and PMMA material,and change the pump light power and temperature to dynamically modulate the optical spectrum.On this basis,this paper carries out systematic numerical simulation and calculation,and analyzes the application prospect of spectrum in power sensors and optical switches.In addition,the numerical simulation proves that the dynamic modulation sensitivity FOM of the temperature control material PMMA can reach 1.7,and the structure can also achieve a fast light effect of 0.34 ps.2.In graphene nanoribbon waveguide system,nanoscale integrated logic gates and a refractive index sensor both based on the tunable plasmon induced absorption(PIA)effect are proposed and investigated by employing a plasmonic waveguide nanostructure.Except for the direct and indirect coupling mechanism which is employed to explain the single PIA effect,the transmission of a three-resonators-coupled waveguide system is deduced theoretically to explain the dual PIA effects.Our calculated results prove that high tunability in wavelength and amplitude of the PIA effect can be achieved by tuning the Fermi levels of the graphene nanoribbons.By taking advantage of the interferometric effect,the logic gates are realized in this ultracompact structure based on the PIA effect in the mid-infrared region.The numerical results reveal that,for the plasmonic logic gate with coupling length of 60 nm,a high extinction ratio(>23.5 dB)can be achieved within a footprint of less than 0.06 ?m2.Moreover,a plasmonic refractive index sensor with sensitivity as high as 1870 nm/RIU is also numerically predicted in this graphene-based waveguide system.In summary,this paper conducts in-depth research and analysis on the PIA effects in two different structures.By combining the formation mechanism of the PIA effect with the dynamic adjustability of the spectrum,the corresponding physical model is constructed,which provides a theory for dynamically regulating the PIA effect.The numerical simulation will provide practical guidance for the design of all-optical tunable photonic devices based on PIA effect,resulting in a more extensive application of optical switch,optical sensing,fast light,quantum information and so on.