This chapter presents a survey oλ recent achievements oλ the ITMO University (St. Petersburμ, Russia) in developinμ new holoμraphic media such as luoride, chloride, and bromide silicate photo-thermo-reλractive (PTR) μlasses as well as the holoμraphic difractive optical elements that are the volume "raμμ μratinμs recorded in the μlasses λor improvinμ dramatically the parameters oλ laser systems oλ diferent types. The photo-thermo-induced crystallization process and the properties oλ luoride, chloride, and bromide PTR μlasses are demonstrated. This new technoloμy enabled recordinμ hiμh-eiciency phase volume holoμrams in the optical quality silicate μlass. These holoμrams are used λor developinμ a number oλ unique difractive optical elements that provide new opportunities λor the laser technique. Some examples oλ desiμninμ and λabricatinμ oλ holoμraphic optical elements such as the super-narrowband ilters λor solid-state lasers and laser diodes, laser beam combiners, and collimator siμhts are demonstrated in this chapter. It is shown that the PTR μlass doped with rare earth ions can be used λor desiμninμ lasers with "raμμ relectors and distributed λeedback.

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Today, silicate photothermorefractive (PTR) glasses are well known as a holographic medium for fabrication of holographic volume diffractive optical elements. The photothermoinduced crystallization process is used for recording high-efficiency phase volume holograms in this material. These holograms are used for developing unique diffractive optical elements that provide new opportunities for the laser technique, for example, narrowband filters for solid-state lasers and laser diodes, beam combiners, holographic collimator sights, chirped gratings for laser pulse compression, etc. By now, the photothermoinduced crystallization and properties of the PTR glass are investigated well enough. However, there are some issues and features still, which are solved in the present work. The mechanism of refractive index change in fluoride photothermorefractive glass during photothermoinduced crystallization and refractive index profile of the volume Bragg gratings were discussed. We studied a fine structure of a core-shell system inside fluoride PTR glass in which a silver nanoparticle presents the core and crystalline phases of silver bromide and sodium fluoride present the shell. We report on the optical properties of volume Bragg gratings in chloride PTR glass after femtosecond laser bleaching. We demonstrated that the bleaching procedure significantly reduces the absorption and increases the thermal stability of the Bragg gratings.