| The fast evolution of lasers and optical communications stimulated increasing demands for diffractive optical elements serving as different types of spectral and angular filters. Extensive research for high-power system make demand for optical device with high destroy threshold value. And traditional surface scored grating in super elevation power In the optical system, will be damaged that grating will destroy threshold value, because it's destroy threshold unable to meet ultra high-power. So there is volume grating with high destroy threshold value that cause extensive attention and application.In the seventies of last century, the advantage of preparing volume grating in the bulk photosensitive material of through the refracting rate is very clear, there are a large number of patents and literatures regarding the volume grating. In these decades, various photosensitive materials are being succeeded in developing constantly: silver halide photographic emulsions, dichromated gelatin, photoresists, photopolymers, photothermoplastics, polymers with spectral hole-burning, and photo-refractive crystals. But these materials will shrink in the process of thermal development, and very sensitive to the humidity, can't bear the radiation of the laser of high power. So the material which prepares the ideal holographic grating puts forward very high requirement to us: It should have and use spectrum alternative that the laser wavelength well match, linear transfer characteristic, high resolution ratio and low noise, high destroying threshold value and can utilize again and again. This text directs against this question, prepare Photo-Thermo-Refractive glass with good optical performance and high destroy threshold value, so that it can be used in the holographic record of the three-dimension for the preparation for Volume Bragg Grating.It is based on Stookey's mixed fluoride sodium glass system for us to adopt, design prescriptions on the basis of SiO2-Na2O-Al2O3-ZnO for the glass main component and a series of glass doped with CeO2, AgNO3 and NaF etc. melted at about 1450℃, the glass have good optical property (homogeneity, without bubble and stripe, high transparency ). Then annealed at 520-640℃. Then we observe analyzing the crystallization characteristic of glass, use XRD and DSC to analyze the component of micro crystal, analyzing the different ability of crystallization in glass samples.We prepared a series of different formula percentage of the samples, and take the flux, nucleating agents, different fluoride formula discussed the parameters of glass samples crystallization of the impact.It show that B2O3 take little work for lowering viscosity at high temperature condition, but at a lower temperature it will reduce the viscosity of samples, it makes the samples after the heat treatment to soften. Therefore, in our sample preparation in the PTR will not introduce B2O3.Through contrast the effect of different nucleating agent Ag and Ti for the ability of crystallization in the samples, is determined Ag is the best choice for the PTR glass's nuclei.In the use of fluoride content in a series of different samples and test contrast, we conclude that: When the F content is low, after the heat treatment involved in the formation of NaF-microcrystal will be seriously inadequate, heat treatment can not be observed after the crystallization, when the F content Too high, the sample crystallize fully when glass is poured, does not have practical value. Only when the F content control at a reasonable scope, the system can make a good photosensitive crystallization properties.
|
PDF Full Text Request