Research On Multi-narrowband Sensor Based On LSPR

In recent years,because of the simple structure,wavelength,intensity,phase tunable vibration response and so on,localized surface plasmon resonance(LSPR)sensor has attracted extensive attention in many application fields,such as biosensor,energy collector,photodetector,near-field scanning optical microscope and so on.LSPR multi-narrowband sensor with their extremely narrow spectral lines can achieve excellent sensing characteristics,and multi-band characteristics can be used as multi-band optical switches and multi-band detection,these characteristics make the study of multi-narrowband sensors of great significance.The main research contents of this paper include:1.A plasmon induced transparent multi-narrowband structure based on the coupling principle of LSPR of metal nanoparticles and waveguide modes is proposed and studied.The structure is constructed of gold nanoparticles and Al₂O₃-Si O₂nanofilms.The extinction spectroscopy method for calculating metal nanoparticles is introduced to obtain the resonance wavelengths of the localized surface plasmon(LSP)of the nanoparticles.The relationship between the waveguide layer thickness and the guided mode is obtained by changing the thickness of the planar waveguide layer.Among them,the E-shaped gold nanostructures can excite quasi guided modes,resulting in multiple Fano shaped transmissions.The structure exhibits multi-narrowband transparency and high reflectance,which is easy to prepare and integrate.2.A multi-narrowband tunable sensor based on plasmon induced transparency is proposed and studied.Covering graphene on the waveguide layer exhibited the tunable function of the structure with tuning range up to 27 nm.In the refractive index range of 1.3?1.39,the figure of merit FOM*of the sensor can reach 66548.At the same time,it can also be used as a multi-band optical switch with modulation depth up to 70%.3.A multi-narrowband polarization independent composite perfect absorber based on LSPR is proposed and studied.The absorber is composed of rectangular gold nano cube and Si O₂-Al₂O₃-PDMS composite structure.Resonant waveguide mode,surface plasmon polariton(SPP)and Fabry Perot(FP)cavity mode are excited in gold nano array Si O₂-Al₂O₃structure.The designed absorber has multi-narrowband of absorption.Through the Al₂O₃reflective layer,the absorption efficiency can exceed96%,and there is no need for any metal reflection layer to improve the absorption efficiency.The structure was analyzed for absorption characteristics into a perfect absorber at different oblique incidence angles and polarization azimuths,respectively,which can maintain the high absorption efficiency at large angles as well as the polarization independent characteristics.In addition,the perfect absorber also exhibits high sensitivity S=319nm/RIU.