Study On The Enhancement And Sensing Of Magnetic Plasmon Resonance In Metamaterials

Surface plasmon resonance(SPR)sensor is an effective technology to detect small environmental refractive index changes on the surface of metal chips.It is widely used in biomedicine,health monitoring,environmental detection and other fields.In recent years,the research of biosensors of magnetic surface plasmons(MSPs)based on metamaterials has attracted more and more attention,but the related research reports are relatively few.This is because the magnetic field component of light contributes almost nothing to the interaction between light and matter.In nanophotonics,obtaining huge magnetic field enhancement has important applications in many fields.In this thesis,surface plasmon polaritons(SPPs)are introduced into the metamaterials.By regulating the period of metal nanowire array in the metamaterials,SPPs and MSPs are strongly coupled to obtain huge electromagnetic fields.The electromagnetic field enhancement effect is applied to biosensor.In this thesis,we firstly introduced the basic concept,principle,characteristics and applications of surface plasmons in detail.Then the basic concepts of metamaterials,negative refractive index materials,MSPs and the principle and application of MSPs based on metamaterials are introduced.Finally,we have designed two kinds of high performance refractive index biosensors based on metamaterials are designed.The content of the thesis includes the following two aspects:1.We propose a metamaterial consisting of a periodic array of cross-shaped holes in a silver substrate.The research results show that by tuning the period of cross-shaped holes,the position of SPPs can be effectively adjusted.When the position of SPPs and the position of resonance of crossshaped holes in the silver substrate approaches,both of them will produce strong coupling,and thus exhibit narrow-band hybrid model on the absorption spectrum as well as huge electromagnetic field enhancement effect in silver substrate surface.In addition,it is found that the metamaterials can achieve perfect absorption of ultra-narrow band in the infrared region,and the full width at half maximum is only 1.74 nm.Therefore,the refractive index biosensor designed based on the metamaterials has very high sensing performance with its sensing sensitivity up to 1317 nm/RIU and a large figure of merit reaching to 756.The above research results confirm that it has potential applications in biomedical sensing field.2.We have designed a magneto-optic refractive index sensor based on metamaterials,which is composed of gold nanowire array/ultra-thin magnetic dielectric film spacer/gold substrate(MIM)sandwich structure.It is found that when incident polarized light is incident at a certain angle,tuning the period of the array can make the SPPs propagating along the surface of the gold substrate are strongly coupled with MSPs excited in the gold nanowire array/gold substrate,and two hybrid modes with ultra-narrow bandwidths will appear in the reflection spectrum.Due to the huge magnetic field enhancement generated by the hybrid mode,up to 26% TMOKE signal can be obtained in the ultrathin magnetic dielectric film with a thickness of only 30 nm.In addition,the TMOKE spectrum of this metamaterials exhibited an obvious Fano line,which leads to the design of the magneto-optic refractive index sensor with very high sensing performance.The sensor sensitivity is up to 896nm/RIU and 650 nm/RIU,and figure of merit is up to 11576 and 33.These results prove that this kind of magneto-optic refractive index sensor based on metamaterials has potential applications in biomedical field.