Ion assisted deposition of optical and protective coatings for heavy metal fluoride glass

Heavy metal fluoride glass materials are attractive for optical applications in the near UV through IR wavelength regions. However, many compositions are relatively soft and hygroscopic and possess low softening temperature (250–300°C). We have applied ion assisted deposition (IAD) techniques to deposit MgF2, SiO2, and A12O3/SiO2 thin filmstructures on fluorideglass substrates at ambient substrate temperature (~100°C). The coatings deposited using IAD improve the environmental durability of the fluoride glass and appear to have reasonably good optical characteristics; without application of IAD, the deposited coatingsare not durable and have poor adhesion.