Latest achievements in chemical composition optimization of photo-thermo-refractive glass and its applications

Abstract

Review on latest modification applappliedied to chemical composition of PTR glass was made. Advancements of updated chemical composition of PTR glass was shown in comparison with commercially produced glass. Such properties as refractive index change, optimal exposition and optical losses in visible range for the glass with recorded hologram was studied. In work samples of two chemical compositions were studied. Conditions of matching included equal regimes of thermal treatment and expose dosages as well as optimized parameters for each composition. Also the study of holograms received at optimal parameters for each glass was made on three different wavelengths. Moreover several new applications for holograms on a modified PTR glass were tested: such as holographic marks in telescopic systems and complex linked holograms. Due to high transparency in visible range, PTR glass now can be applied for creating holographic marks in telescopic systems. Studies show transparency of 92% with Fresnel losses. Also it is found that spectral selectivity is maintained for such holograms, thus it is opening a new way of optical solutions in telescopic systems. As it was measured, spectral selectivity of recorded hologram corresponds to 400mkm efficient thickness according to calculations. Though, it needs further studies to increase the effective thickness of such holograms as well as investigations of different Bragg angles at recording step. Complex (linked) holography is another way of multiplexing inside a bulk glass. It leads to combination of reflecting and transmitting Bragg gratings as a unite element with proper functions. This, for instance, can provide positive feedback for complexes of laser diode crystals on a small size site. Simultaneously, such element can combine emission from all emitting surfaces in one beam. This study may lead to creation of high power coherent diode laser sources at small size site with ultra-narrow emitting bandwidth and high quality spatial beam characteristics.