Volume grating recording in fluorinated silicate glasses

Sodium-zinc-aluminum-silicate glasses doped with silver, cerium, fluorine, and bromine were melted in 100 cc fused silica crucibles in an electrical furnace. The polished glass plates were exposed to UV radiation of a He-Cd laser at 325 nm. Spatial frequencies of the interference patterns written ranged from 500 to 700 l/mm. Exposed samples under went heat treatment at temperatures from 500 to 520 °C to produce photoinduced crystallization. The thickness of gratings formed were from 1 mm to 10 mm. High diffraction efficiencies up to 75% and losses less than 10% have been obtained in these glasses for exposure doses of 100 mJ/cm2. The dependence of the grating properties on glass composition and thermodevelopment schedule is studied.