Kryvonosov I. The growth of Ti-sapphire in carbon medium meant for tunable lasers.

The thesis is devoted to development of technological foundations for the growth of Ti-sapphire single crystals in carbon medium meant for tunable lasers, as well as to creation of new technological methods which increase the quality of active laser elements. Comprehensive study of the influence of the gas medium with different chemical potential on the optical, structural and mechanical characteristics of Al2O3:Ti (Ti-sapphire) single crystals, was performed. Investigated was the influence of ultrasound with different frequency on accumulation of gas bubbles in the melt and on pore creation in the crystal. The nature and mechanism of formation of submicron and faceted micron inclusions in the Ti-sapphire grown in carbon medium, were studied. The technological possibilities for the growth of Ti-sapphire by the Czochralski, Stepanov and HDM methods, were considered. Technical decisions for the increase of the grown crystal quality were proposed. The scintillation properties of Ti-sapphire with different activator concentrations, were studied. The content of titanium in the crystal of about 600-800 ppm was established to provide the maximum scintillation light yield of Ti-sapphire, and to allow its use in detectors of a-particles thermal neutrons and electrons.