Development Of Film In 278nm All-solid-state Laser System

As the greatest inventions of the 20 th century,the laser has already become one of the important symbols to weigh the comprehensive strength of the country.Because of its compact,high energy,high beam quality,good work stability and so on,UV all-solid-state lasers have been widely used in the fields of national defense,precision processing,medical treatment and scientific research.Based on the excellent characteristics of the CBO crystal,the 278 nm all-solid-state laser system is desired to achieve a novel high power short-ultraviolet DPL with excellent application performances.In order to achieve the technical requirements of the 278 nm laser system,Hafnium and UV-Si O2 were selected as thin-film materials,a separation film for frequency doubling and a high reflective optical thin films was developed on the JGS1 substrate to separate the double frequency laser and the quadruple frequency laser.Based on the analysis of the regularity of spectral performance with the periodicity of the film system,combined with the influence of the electric field intensity on the laser damage threshold and optical loss of the thin film,the optimal design of the film system was completed.With a variety of testing methods and analysis software,the film deposition process was optimized through comparative experiments,and the optical loss caused by process factors was reduced.By exploring the preparation process of the film,a detailed substrate cleaning process was formulated;a procedure for fully premelting the film material was set;a suitable film thickness monitoring method was selected;and the process parameters of ion source cleaning and auxiliary deposition were optimized.By analyzing the spectrum of the test strip,the main factors causing the error are analyzed.Developed effective plan to reduce film thickness control error.At the incident angle of 45°,the frequency doubling separation film has a transmittance of 98.82% at 278 nm,a reflectance of 99.80% at a wavelength of556 nm,and the high reflective optical thin film with a reflectance of 99.60% at 278 nm.The average value of the spectrum in the range of 40°to 50°meets the technical parameters.The laser damage threshold of the frequency doubling separation film is 12.53J/cm2 and the high reflection film is 14.41J/cm2.It has good resistance to laser damage and excellent environmental resistance.