Laser crystal analysis using the OLCAO electronic structure method

This work investigates the theoretical analysis of laser crystals through the band structure method of Orthogonalized Linear Combination of Atomic Orbitals. A review of the more traditional theoretical method, the Crystal Field Theory, is provided for comparison with the Orthogonalized Linear Combination of Atomic Orbitals theory. The benefits of the more computationally intensive band structure method in analyzing the complicated crystal structures typical of laser materials are presented. The method is then utilized to study Cr4+-doped yttrium aluminum garnet and its application as a passive Q-switch device. The detailed analysis provided by the Orthogonalized Linear Combination of Atomic Orbitals method leads to an alternate model for optical transitions within the passive Q-switch application, and experimental evidence validating this model is presented. The method is then used to study undoped, bulk yttrium aluminum garnet and gadolinium scandium gallium garnet crystals with emphasis on the radiation hardness of laser rods using these hosts. Plans for future work are presented, including a suggestion of how this powerful theoretical method can be used in a predictive mode to facilitate the design of novel laser materials.