Narrow Band Anti-transmission Mode And Application Research Based On Metasurface

Metasurface is a special kind of metamaterial,which has a two-dimensional or planar structure.Up to date,metasurface is not found in nature and is generally a kind of artificial materials.Therefore,some of its special properties are not available in natural materials,such as negative permeability and negative permittivity.Through reasonable design of its structure and size,it can be widely used in many fields.Surface plasmon polariton(SPP)is a special type of surface wave that exists on a metal–dielectric interface.In the optical regime,the electromagnetic(EM)field of incident waves interacts with the plasma of electrons near the surface of the metal and therefore excites collective oscillations propagating along the interface.The interaction is so strong that the EM field is tightly confined to the interface.Because the metal is highly conductive,the electric vector must possess a component normal to the interface.The ability of SPPs to break the conventional diffraction limit provides a most promising method to achieve highly integrated optical circuits in nanoscale devices,which has attracted widespread attention.In recent years,it is shown that an electromagnetically induced transparency(EIT)-like effect,known as plasmon-induced transparency(PIT),can occur in some SPP-based structures.However,compared with EIT,PIT is considered as one of the alternatives to EIT due to its large bandwidth,easy integration with nano-plasma structures,and ability to operate at room temperature.Opposite to the PIT modes,narrow anti-transparency(PIAT)modes in a wide opaque band can exist and expect to have wide applications also.At present,not much attention has been paid to PIAT.In this paper,a metallic metasurface is proposed on a dielectric substrate whose unit cell consists of double two-split nanorings.Through breaking symmetry by rotating in opposite directions in the nanoring,multiple resonance modes are formed in the transmission spectrum.In 1198.2nm,a sharp resonance mode appears,considered as PIAT mode.Moreover,a PIT mode appears at 1522.2nm.A unified mechanism for generating the PIAT and PIT resonances are studied.This is because the incident light interacts with electrons and excites plasmonic waves which propagate along the metallic rings.Under certain conditions,the plasmonic wave can be in resonance in the rings.The coupling of modes accumulated by split rings can result in self cancellation or self strengthening.The appearance of PIAT mode is due to the self-cancellation of the plasma wave.A PIT mode is a self-enhancing plasma wave.The dependence of the transmission characteristics of designed split resonant ring device on the geometric parameters is studied in detail by changing the Split ring's split width,rotation angle,split ring size and by changing the symmetry of the structure.Increasing the width of the nanoring split will increase the intensity of the PIAT and PIT modes.These resonances are highly sensitive to the type of background materials.We explored its applications in sensing.The figure of merit is 127,the FOM can reach 57 and the minimum measurable refractive index is 0.0077.The sensitivity is up to 710 nm / RIU.It has a reference for designing a highly sensitive background refractive index sensor.In theory,it can provide a platform for biosensing,which can be used to tell cancerous tissues from healthy tissues.