Near-field Enhancement And Far-field Modulation Of Large-area Micro/Nano Structures Based On Surface Plasmons

Surface plasmon is an effect of oscillation of free electron on metal surface under light.Related research has been studied since the discovery of surface plasmon phenomena in the 1960 s.Surface plasmons have many special properties such as a strong electromagnetic field enhancement effect within a small spatial scale.Surface plasmons can also modulate the optical response of the far field by the frequency selective effect on the incident light.These properties make surface plasmons a very important part of nano-optics.In recent years,with the exploration of researchers,surface plasmons have not only been limited to the field of nano-optics,but also have been cross-developed with many fields such as biological detection,chemical analysis,materials science,and information technology,surface plasmon become the important parts of many frontiers and the core component of science and technology.This thesis focuses on the surface plasmon effect generated by large-area micro/nano structures.Combined with experimental results and theoretical analysis,the near-field enhancement effect and farfield modulation effect of surface plasmons are studied.Specifically,the research of this paper is mainly focus on the following two aspects.Firstly,for near-field enhancement effects,we designed and studied a dual-layer metallic grating nanostructure.This designed dual-layer metallic grating structure can generate electric field enhancement caused by surface plasmons,and simultaneously generate optical cavity mode to enhance local electromagnetic field.The enhanced electric fields are not limited to metal surfaces.By changing the structural parameters of the dual-layer metallic gratings,by the simulation calculation and analysis,we studied the effects of different electromagnetic field enhancement modes.This electric field enhancement effect,which is not limited to the surface of the metal grating,can improve the original Raman signal enhancement effect and greatly reduce the time of molecular adsorption on the grating surface,realizing the instant detection of the Raman signal.The nanostructure prepared by the nano fabrication processing method which is from top to bottom also has good uniformity,stability and reproducibility,and the utility of the Raman detection can be greatly increased by the combination with the microfluidic system.In addition,we have also measured the enhancement of the fluorescence signal of the adsorbed molecules on the metal surface,laying the foundation for future studies of biological detection.Secondly,for far-field modulation effects,we studied the effect of infrared radiation by the surface plasmon effect of silica microspheres,and mixed the silica microspheres into the porous organic polymer material.This material can efficiently perform the radiative effect in the atmospheric window.The infrared radiation material achieves better radiation cooling effect,and can achieve a cooling effect close to 10 degrees compared with the outside air temperature during the daytime.At the same time,we measured the power and cooling effect of radiant cooling,and explored the practical application of radiant cooling.In addition,we have also studied metal nanostructures that can modulate the wavelength of reflected light,and have proposed two processing schemes that can mass produce these colored nanostructures.In this paper,the effects of surface plasmon on large-area micro/nano structures are studied in combination with theory and experiments.The near-field enhancement effects and far-field modulation effects are studied in depth.Based on the top-down nanofabrication processing method,the batch preparation of large-area micro/nano structure was studied.The work of this paper has deepened the understanding of surface plasmons and laid the foundation for the future practical application of surface plasmon-based superstructures.