Abstract

Unlike Nd lasers, 2.0 μm lasers are complicated by the presence of a sensitizer as well as an active atom, by the plethora of energy levels associated with Ho and Tm, and by the quasi three level laser operation. With two different atoms in the laser material, each having a multitude of manifolds and levels, several energy transfer processes are possible. Some of these energy transfer processes are necessary for the efficient operation, while others are clearly deleterious. Understanding all three of these effects is aided by a quantum mechanical model of the various atoms. In addition, quantum mechanics is used to unravel the spectroscopy of the laser material. Consequently, a quantum model is highly useful in understanding the physics of existing lasers and to help predict new laser materials with high potential. A quantum mechanical model can be used to unravel the spectroscopy of the Ho and Tm atoms either with ab initio calculations or by using an iterative approach with experimental data. With either method, energy levels, degeneracies, and transition probabilities can be determined. These directly affect pertinent ground state absorption and every transfer process, including upconversion. Details of these calculations will be given.

© 1992 Optical Society of America