Design And Simulation Of One-dimensional Photonic Crystal Devices In Biology Field

The different dielectric materials are arranged periodically,thus a band structure in the modulation of the Bragg scattering with the propagation of the electromagnetic wave in the medium is formed.The band gap is appeared in the different photonic crystal band.Within the band gap the electromagnetic wave at the wavelength cannot pass.It is called photonic band gap(PBG).Photonic crystals are a new kind of materials with photonic and gap.The appearance of photonic crystals is not only with strong theoretical significance,but also has a vast potential for future development.One-dimensional photonic crystal is refers to the structure that the materials with different refractive index(or dielectric constants)are arranged periodically only in one dimensional space direction,and the membrane layer is homogeneous and infinite extension in two-dimensional direction.So the photonic band gap will appear in one dimensional direction which changes periodically.Based on the calculation methods used in electromagnetic field and optics film theory,firstly,this paper studies the various factors affecting the transmission characteristics of one-dimensional photonic crystals and its photonic band gap in the normal incidence of light.And then in the same condition,introduce defects in one-dimensional photonic crystals,analyze the transmission characteristics.Finally based on the features,one-dimensional photonic crystal is applied to biology.According to the analysis of numerical simulation,improving the structure of the model or material parameters to make the design more perfect.This paper mainly covers the aspects as following:1.Currently,the inorganic sunscreen materials are mostly to be analyzed or applied directly by experiments,the validation of its verify its anti-ultraviolet function is rarely employing numerical simulation.Based on the theories of optical films and the knowledge of photonic crystal structures,three kinds of inorganic sunscreens are selected to combine and design two nano-films,then the UV transmittance curve is calculated with FDTD method.Through observation the transmittance curve ranging with wavelength of those nano-films in the ultraviolet area,the authors find that the two photonic crystal nanometer films can produce a band gap of different wavelength coverage.Most of the ultraviolet light is reflected in the band gap,making the transmittance nearly zero.Thus anti-UV function of the inorganic sunscreen TiO2,SiO2,ZnO is verified theoretically.And at the same time,by calculation,we achieve the design purpose of UV protection of nano-films.The simulation results of these inorganic sunscreens provide a theoretical basis for the umbrellas coating,anti-UV nano packaging,basking prevention in garment fabric and cosmetic applications.Then through their own superposition of two film piles,nano-films expand the band gap width effectively,making almost the entire ultraviolet wavelengths are in the forbidden band range.This optimize UV protection function of the film.2.After single defect is introduced into one-dimensional photonic crystal,the PBG will have a very thin transparent window.In the window the wave can penetrate,while the rest are still banned in the PBG.The transparent window is called photonic crystal defect modes.After detailed analysis of factors influencing the defect mode,using TiO2 and siO2 as high refractive index medium and low refractive index medium respectively to design a new solution concentration detection sensors.And the detection sensors is used for sucrose solution to simulation and data fitting.Refractive index of different concentrations of sucrose solution are different,by refractive index for intermediate parameters,the solution concentration has something to do with the peak of the defect modes in the initial model.The refractive index increases with the concentration of the sucrose solution,the peak of defect modes in the forbidden band of one-dimensional photonic crystal detection sensor will gradually decreases.And thus the change of the peak of defect modes can be to represent the size of the solution concentration.After simulation,a function of the peak and solution concentration is obtained by fitting simulation data.Then change the initial model to futher optimization,the concentration of sucrose solution is combined with the change of the position of defect modes appeared.The greater the sucrose concentration is,the further towards long wave the position of the defect modes appeared in the forbidden band is moving,and the larger distinguish range is.Thus we can use the different location of defect modes to represent the solution concentration.After optimization,the model can reflect more the sensitive features of one-dimensional photonic crystal for defect dielectric refractive index.The geometric thickness of dielectric micro cavity in the middle is fixed so that it is easier to be made.