Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)




Guzin Armagan


This research comprises a comprehensive spectroscopic study of the characteristics of the solid state crystal YAG (Yttrium Aluminum Garnet) singly doped with Ho (Holmium) ions. An important area of solid state laser crystal research is the determination and optimization of the processes within these laser crystals which lead to efficient laser action. In most laser crystals, there is a donor ion such as Tm (Thulium) and an acceptor ion such as Ho. The donor ion generally has greater absorption than that of the acceptor at the wavelength of the pump source. The donor ion can transfer this absorbed energy to the lasing manifold, {dollar}\rm\sp5 I\sb7{dollar}, of the Ho acceptor ion. A loss process to the 2.1{dollar}\mu{dollar}m laser emission from the {dollar}\rm\sp5 I\sb7{dollar} manifold is the radiative energy transfer of this emission to a neighboring Ho ion. The purpose of this research is to determine the dependence of this radiative energy transfer process on various macroscopic parameters of the YAG:Ho crystals.;Spectral and kinetic data were acquired over a wide range of temperatures and excitation points of the four samples available: YAG:Ho (8.5%), (3%), (1%), and (0.32%). The spectral data include absorption and luminescence. The kinetic data consist of the temporal responses to pulsed excitation.;Models for the spectral and kinetic data were developed and found to agree closely with experimental results. Moreover, these models successfully correlated the Ho-Ho radiative energy transfer with the concentration, temperature, and excitation position parameters of the YAG:Ho crystals. Using these models, one can minimize this loss process by choosing the appropriate crystal parameters and thereby, increase the efficiency of laser action.



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