Waldo J. Rodriguez

Energy levels and optical properties of neodymium-doped barium fluorapatite

Energy levels of the 4f3 electronic configuration of Nd3+ in barium fluorapatite, Ba5(PO4)3F(B-FAP) have been determined from polarized absorption and fluorescence spectra using crystals at 8 K. Experimental energy-level assignments were made initially by comparing the crystal spectra energy levels with those obtained from those previously reported for Nd3+ in strontium fluorapatite and fluorapatite. The initial crystal-field parameters were calculated by using lattice summation techniques. The crystal-field parameters were varied to obtain a best fit between experimental and theoretical energies and the final values give a root-mean-square deviation of 7.1 cm−1. The odd-fold crystal-field components are used to calculate the emission intensities and lifetimes of the Nd3+ ions in B-FAP. These calculations yield results in good agreement with the experimental measurements of the absorption and emission cross sections and lifetimes.

1.75 µm Pumped Ho:Tm:LuAG High Efficiency Laser

Large improvements in the slope efficiencies and thresholds of Ho:Tm:LuAG with small changes in temperature are investigated. The temperature relation between the upper laser level storage time, upconversion, and slope efficiencies is observed.

Spectroscopy and Development of Solid State Lasers at NASA

NASA Langley has developed expeditious methods of evaluating new laser materials and laser systems using quantum mechanical and energy transfer models. Veracity of these models has been tested against measured spectroscopic parameters as well as measured laser amplifier performance. In particular, these methods have been applied to the development of 2.0 µm laser such as the Ho:Tm laser materials.

Modeling and Performance of 2.0 μm Lasers Projections for Remote Wind Sensing

A series of models has been developed and experimentally verified which predicts the performance of Ho:Tm lasers operating around 2.1 µm. Using these models, a Ho:Tm:YLF laser system suitable for the remote sensing of wind speed was optimized and characterized. Results are used to project the performance of satellite borne wind speed sensors as well as to predict performance of new laser materials developed at NASA, such as Ho:Tm:LuAG and Ho:Tm:LuLF.