Part of the book: Advanced Photonic Sciences
This chapter presents a survey of recent achievements of the ITMO University (St. Petersburg, Russia) in developing new holographic media such as fluoride, chloride, and bromide silicate photo-thermo-refractive (PTR) glasses as well as the holographic diffractive optical elements that are the volume Bragg gratings recorded in the glasses for improving dramatically the parameters of laser systems of different types. The photo-thermo-induced crystallization process and the properties of fluoride, chloride, and bromide PTR glasses are demonstrated. This new technology enabled recording high-efficiency phase volume holograms in the optical quality silicate glass. These holograms are used for developing a number of unique diffractive optical elements that provide new opportunities for the laser technique. Some examples of designing and fabricating of holographic optical elements such as the super-narrowband filters for solid-state lasers and laser diodes, laser beam combiners, and collimator sights are demonstrated in this chapter. It is shown that the PTR glass doped with rare earth ions can be used for designing lasers with Bragg reflectors and distributed feedback.
Part of the book: Holographic Materials and Optical Systems
In this study, the luminescent properties of the CdS(Se) quantum dots (QDs) with the mean size of 2–4 nm, the (PbS)n/(PbSe)n molecular clusters (MCs) and PbS(Se) quantum dots (QDs) with the mean size of 2–5 nm embedded in the fluorine-phosphate glass are investigated. The dependence of the photo luminescence absolute quantum yield (PL AQY) on the sizes of the CdS(Se) QDs are studied. It is found that the PL AQY of the CdSe QDs increases monotonically to its maximum height and then falls down. The PL AQY of the CdS(Se) QDs can reach 50–65%. Luminescence of (PbS)n/(PbSe)n MCs embedded in fluorine-phosphate matrix and excited by UV radiation is obtained in the visible spectral region and its absolute quantum yield was up to 10%. The PbSe QDs have broadband photoluminescence with quantum efficiency about five times more than MCs (~50%) in the spectral range of 1–1.7 µm. Glasses doped with PbS(Se) QDs provide potential application as infrared fluorophores, which are both efficient and possess short life times. The glass matrix protects the QDs from external influence and their optical properties remain unchanged for a long time.
Part of the book: Quantum-dot Based Light-emitting Diodes
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.
Part of the book: Holographic Materials and Applications