Research On Surface Plasmon-Induced Transparency And Slow Light Effect Based On Graphene

Surface plasmon is a collective oscillating wave propagating along the surface of a conductor caused by the interaction of photons and free electrons.It can cause special optical phenomena on metamaterials such as graphene under certain excitation conditions and wavelength bands,such as negative Refraction,plasmon-induced transparency(PIT)and slow light effects.Graphene has obvious advantages over traditional noble metal metamaterials.It has extremely high wave momentum,low energy loss,and most importantly,flexible electronic modulation.Surface plasmon is a combination of electronics and photonics and has caused extensive research at home and abroad.For graphene materials,this paper mainly studies the PIT effect and slow light effect caused by the surface of metamaterials.The main research work is as follows:The PIT phenomenon is induced by constructing a metamaterial structure in which a disc is combined with a side ring by a bright mode-dark mode coupling method.The graphene disk can be directly excited by incident light as a dipole resonant bright mode,while the graphene side strip can not be directly excited by incident light as a dark mode,but can be indirectly excited by a strong near-field coupling between the disk and the two side bars.And is excited into a quadrupole resonance mode.Finally,a clear transparent window is created between the two resonance troughs,realizing the PIT effect based on the coupling of the bright mode and the dark mode.Based on this,the geometric parameters affecting the change of PIT are discussed.The gap distance g and the moving distance s of the disc can change the coupling strength of the bright and dark modes.The change of the coupling intensity can adjust the transparency and bandwidth of the PIT window.Adjusting the conductivity of graphene can change the Fermi energy of graphene,and the Fermi energy change can also adjust the PIT effect,and the maximum transmittance of incident light reaches 97%.A system based on graphene metamaterials with adjustable PIT and slow light effects was designed and studied.By changing the positional parameters of the metamaterial structure and the Fermi energy,the PIT transparent window can be actively adjusted.By phase shift calculation,the ability to actively adjust the slow light is realized at the transparent window,and the maximum group delay of the light reaches 0.19ps.Under the condition that the Fermi energy is constant,the relationship between the group delay of light and the coupling strength between bright and dark modes is analyzed and verified:the stronger the coupling strength,the faster the group speed of light;the weaker the coupling strength,the higher the group speed of light.slow.The research to achieve slow light control has a positive effect on solving the new generation of optical communication and enhancing the competitiveness of the information industry.