Effect of UV-Irradiation on Sol-Gel Optical Films

Sol-gel optical films were deposited on K9 glass and silicon wafer substrates by spin-coating method and a high-pressure mercury lamp was used to perform ultraviolet treating to solidify these films and improve their performance.SEM,AFM,IR and ellipsometer were used to characterize the structure and optical properties of the films.Mechanical property of films was measured by pencil hardness-testing device.Laser damage threshold of films was measured by a Q-switched Nd:YAG high power laser with the wave length of 1 064 nm and the pulse width of 15 ns.The results show that UV-irradiation can improve the mechanical property and increase the refractive index of the films.Besides,the nodules on the surface of the films can be changed into pits by UVirradiation process,so the laser damage threshold of sol-gel thin films will be increased.After UV-irradiation the laser damage threshold of single-layer ZrO_2 film reached 50.6 J/cm~2(1 064 nm,1 ns).It is found that UV-irradiation is an effective method to avoid the infiltrating between the layers,and the degree of homogeneity of the multilayer films can be improved by this way.