Process for production of high efficiency volume diffractive elements in photo-thermo-refractive glass

摘要: A novel process is proposed for the volume diffractive element (Bragg grating) fabrication in photosensitive silicate glasses doped with silver, cerium, fluorine, and bromine. The employs a photo-thermo-refractive (PTR) glass of high purity exposed to ultraviolet (UV) radiation He—Cd laser at 325 nm followed by thermal development temperatures from 480° C. 580° C., preferably 520° several minutes hours. Absolute diffraction efficiency up 95% was observed 1 mm thick gratings. Maximum spatial frequency recorded PTR about 10,000 −1 . No decreasing were detected low frequencies. Original transparent (absorption coefficient less than cm ) 350 4100 nm. Induced losses developed decreased 0.3 0.03 between 400 700 nm, respectively, did not exceed 0.01-0.02 infrared (IR) region 2500