Study On The Preparation And Laser Damage Of Sol-Gel Oxide Thin Films

In modern society,laser system plays an important role in scientific research and industrial production.Optical thin film is a kind of common and very important component in laser system,but it is easy to be damaged by laser,which limits the development of laser system.It is of great significance to study how to prepare optical films and improve their ability to resist laser damage.Compared with films prepared by physical methods,sol-gel films have the advantages of high laser damage threshold,no substoichiometric defects,simple process,low cost,and adaptability to substrates of various shapes.By preparing four different sol-gel optical films,they were studied that the effects of additives,annealing temperature,doping process and in-situ high temperature on the properties of the film.The damage mechanism was analyzed,and a method for further increasing the laser damage threshold was explored.First of all,Ta₂O₅ sol was synthesized with TaCl₅ as precursor by using two different double additive combinations,namely,DEA+ACAC,DEA+PEG.Ta₂O₅ thin film was prepared by dip-coating method.The effect on the properties of the films was discussed with different combinations of dual additives and various annealing temperatures?25?,150??.Then the laser induced damage threshold?LIDT?of the two films was measured at 25?and 150?.Finally,the LIDT of Ta₂O₅ film with DEA+PEG additives combination was the highest,reaching 29.1 J/cm²?25??.Second,with acidic and alkaline formulations used,two kinds of sol-gel SiO₂ films were prepared.After that,the films were annealed at 100?and 200?for 1 h.With studying the relationship between different annealing temperatures and various properties of SiO₂ film,it was found that no matter what temperature the alkaline SiO₂film had,the LIDT was higher than acidic SiO₂ film.After annealing at a higher temperature,the LIDT of both films decreased,while the decrease of the alkaline SiO₂film was smaller.Then,using ACAC as the only additive,TiO₂,Al₂O₃ and Ta₂O₅ sol were prepared.TiO₂ sol was mixed with Al₂O₃ sol and Ta₂O₅ sol with element molar ratio Ti:Al:Ta=7:3:3,respectively,to prepare and characterize two kinds of TiO₂ doped films.Experimental results show that one way to effectively improve the LIDT of sol-gel TiO₂film is to dope Al₂O₃ and Ta₂O₅.Finally,using Hf inorganic salt HfCl₄ instead of traditional organic alkoxide,HNO₃ as additive,how to prepare HfO₂ sol-gel film was studied.The HfO₂ thin film was characterized,and its properties were discussed,which laid a foundation for preparation of HfO₂ thin film with higher LIDT.This paper has 35 pictures,7 tables,and 123 references.