Research On Absorption Enhancement Of Metasurface For Micro-nano Structures

Absorption enhancement of micro-nano structures plays an important role in daily life and attracts more and more people's attention in view of the great reduction in the excessive consumption of traditional energy sources and its wide range of applications.This paper mainly focuses on two kinds of applications in absorption enhancement of metasurface for micro-nano structures.One is the study of wide-spectrum polarization-independent absorber by using the effective medium theory and the time-domain finite-difference algorithm to discuss the absorption efficiency,polarization and incident angle in the visible wavelength range and analyze the absorption mechanism with the distribution of electromagnetic field;The other is the study of two-dimensional grating sensor by applying the impedance matching method and the time-domain finite-difference method to discuss absorption characteristics and FOM*value with the changed refractive index of environmental media.The specific work of this paper is as follows:?1?We proposed a wide-spectrum polarization-independent metasurface structure.The average absorption efficiency was higher than 98.91%for both TM and TE polarizations at normal incidence,polarization-independent,and the absorption efficiency was still higher than 95%within the incident angle of 45°.The excellent characteristics of this wide-spectrum polarization-independent absorber were attributed to the existence of the Brewster angle and the gradient index of the structure for TM polarization,and attributed to theSiO₂ antireflection layer and gradient refractive index of the structure for TE polarization.?2?We designed a two-dimensional polarization-independent grating structure,and analyzed the effect of each parameter and the sensing characteristics.The results showed that the absorption efficiency can reach 99%at the wavelength of 818nm at normal incidence.Additionally,the wavelength of absorption peak can be linearly changed and ensure the absorption efficiency at the same time by adjusting the parameters of the grating structure.Within the incident angle of 20°,the absorption characteristics of the structure were insensitive.In addition,the wavelength of absorption peak was very sensitive to refractive index and the values of S,FOM were 753nm/RIU and 19.7,especially,FOM*can exceed 300,this structure has a great sensing ability.This paper has made some contributions in the field of absorption enhancement of metasurfaceformicro-nanostructures.Thedesignedwide-spectrum polarization-independent absorber not only achieved a high absorption efficiency in the visible light range,but also was insensitive to the incident angle.Especially,the characteristic of polarization-independent has been realized,which solves the problem that realizing the polarization-independent absorption with wide spectrum is difficult;The sensitivity of the proposed two-dimensional grating sensor has been improved further,and it can be applied well on refractive index?Refractive Index,RI?sensors.