Research On Surface Enhanced Infrared Substrate And Its Molecular Detection Method Based On Metasurfaces

Surface enhanced infrared absorption spectroscopy can improve the signal strength when detecting molecules by combining the characteristics of infrared spectrum and the enhancement of surface electric field.It is expected to become a high sensitivity and precision detection and analysis method in the fields of analytical chemistry,molecular biology,environmental detection,medical and other scientific and engineering fields.With the rapid development of nano photon technology,the application of SEIRA in molecular detection by designing nano device structure has become a research hotspot of nano photonics.The main contents of this paper are as follows:Firstly,electromagnetic simulation method and optimization algorithm.The structure of the device is simulated by the electromagnetic simulation method(finite element method,spectral element method).The target function of the infrared spectrum data calculated by the two methods is constructed,and the optimal inversion of the molecular optical parameters is realized by combining the genetic algorithm,thus the application prospect of electromagnetic inversion technology in the field of molecular detection is verified.Secondly,the research of surface enhanced infrared substrate and its characteristics based on super structure surface.Combining the metal surface plasmon and the whole dielectric metasurfaces,a new type of metasurfaces based on the coupling effect is proposed,which enables the electromagnetic wave to excite the two modes on it at the same time,and promotes the coupling effect by adjusting the array period.The physical mechanism of the new super structure material and the influence of the periodic adjustment of the array on the physical characteristics such as resonance wavelength,electric field distribution and field enhancement factor are studied.Thirdly,molecular detection technology based on surface enhanced infrared substrate.The sensing performance of the substrate as a refractive index sensor is studied(the refractive index sensitivity is up to 7?m/RIU);the application of the substrate in SEIRA is analyzed,and the detection of molecular fingerprints is realized;finally,the optical constants of molecules are inversed with high precision by using the previous spectral data and combining optimization algorithm and electromagnetic simulation method(the precision is over 94%).