Study On Controllable Spectrum In Wide-wavelength Range Based On Multi-films Structures

Recently,the main purpose of researching and developing optical devices based on micro-nano structures is using various micro-nano structures to control tailoring of the incident spectrum,which can be designed spectral characteristics according to requirements.The optical devices,which have the perfect absorption of a certain wavelength band or only transmission of another certain wavelength band,can be widely used in optical communication,hyperspectral imaging,solar cells,holographic display,structural color and other fields.Because of the advantages of simple process and function with strong tunability,the multi-layer film structure with different metals and dielectric materials is one of the important research directions of low-cost micro-nano optical devices in recent years.This paper has studied mechanism and designed micro/nano-optical devices with multi-layer film structure based on the optical properties of metals and dielectric materials,which can be applied to select different wavelength bands.The research contents of this paper can be referred to develop low cost devices and high-performance optoelectronic device industrialization.The specific research contents of this paper are as follows:1.The transmission filter element based on the cavity dielectric symmetrical distribution structure Ag-Bi Fe O₃-Si O₂-Bi Fe O₃-Ag is studied.The dielectric layer is composed of Bi Fe O₃/Si O₂/Bi Fe O₃.Through the continuous adjustment of the thickness of Si O₂and Bi Fe O₃in the symmetrical dielectric layer,the adjustable function of the visible light range spectrum is realized.The influence of the intermediate dielectric layer on the light transmission is analyzed.Then the influence of the cavity symmetry structure and material on the optical properties is compared and analyzed.The correlation between the wavelength selective transmission of the device and the resonant absorption of the Fabry-Perot microcavity,the polarization independence of the device in the optical field of the incident light and the angle dependence of the incident light are discussed.The direction of improving Metal-Dielectric-Metal（MDM）structural quality is found.By adjusting the thickness of the intermediate symmetrical dielectric layer,a continuously adjustable filter device in the entire visible light band is obtained.2.Based on an asymmetric Fabry-Perot（FP）cavity structure,a near-perfect absorption device with selective infrared wavelength band is proposed.The traditional MDM structure is replaced by a highly reflective Distributed Bragg Reflector（DBR）structure as the upper metal mirror.And the optical Tamm state is excited in the asymmetric FP structure.The roles of the top metal layer and the intermediate dielectric layer in obtaining a wavelength-selective perfect absorber with a high-quality factor are analyzed.The traditional MDM and the structure based on the coupling of optical Tamm state and FP cavity are compared.The optical field control characteristics of the device are simulated by Finite Difference Time Domain（FDTD）and the resonant mode is discussed.And then the absorption characteristics,polarization characteristics,internal electric field distribution,and absorption power density distribution of the two structures are studied.At last,the influence of the DBR structure on the spectrally regulated quality of the infrared wavelength selective spectral modulation devices is obtained and the direction of improving the quality factor of the multilayer nanostructure spectral modulation is pointed out.On this basis,the metal layer Au based on the DBR structure is replaced by Ti N to analyze the optical properties.According to the simulation results,a low-cost and high-quality spectral modulation element in the infrared wavelength range is further proposed.3.A structure Ag-PVDF-Ag based on piezoelectric properties is proposed to achieve filtering effect.The piezoelectric properties of PVDF are discussed.And the filtering structure is simulated.By adjusting the structural parameters,a continuously adjustable transmission spectrum in the visible and infrared range is achieved.The optical field loss is analyzed by the electric field diagram.Then the angle-sensitive characteristics under the two polarizations（TE/TM）are further simulated and analyzed.According to the simulation results,the advantages and disadvantages of the filter device under this working mechanism are analyzed,the further optimization of the structure is discussed.Finally,the experimental preparation and testing of the PVDF film were carried out,and the optical properties of the film which were changed by voltage polarization provide a certain reference value for the realization of the adjustment function of the filter device.