Michael A. Bass

Modeling of high-power solid-state slab lasers

We present practical modeling for edged-pumped high power solid-state slab lasers. Both analytic and ray tracing methods were used to analyze the distributions of absorbed pump power using real broad spectrum diode laser pump sources. The resulting thermal and stress distributions were calculated with finite element analysis. Our analyses include the temperature dependence of the gain medium’s thermal conductivity and expansion coefficient. Nd:YAG and Yb:YAG were then compared for use as gain media for high power solid state slab laser.

Optically written displays based on up-conversion of near-infrared light

Analysis of the process of up-conversion suggest scaling rules for up-conversion based optically written displays. These rules have been demonstrated experimentally and give us confidence in our designs of such displays.

Spectroscopy and lasing performance of Er-doped LiYF4 and KYF4

The spectroscopic properties of Er3+ in the fluoride hosts LiYF4 and KYF4 or YLF and KYF respectively, are presented as they relate to cascade lasing of the 4I11/2 to 4I13/2 and 4I13/2 to 4I15/2 transitions. In this manner simultaneous lasing at near 2800 and 1600 nm is obtained.

Growth and characterization of pure Cr; Cr,Er and Cr,Ho codoped Y2SiO5

The Czochralski crystal growth of pure Cr, Er and Ho doped as well as Cr,Er and Cr,Ho codoped yttrium silicate Y2SiO5 (YSO) is reported. The growth conditions for producing the inclusion free single crystals of high optical quality are discussed. Spectroscopic properties of the singly doped and codoped material at room temperature are compared. Energy transfer processes from Cr4+ ions to Ho3+ and Er3+ ions in YSO host have been demonstrated for the first time.

Spectroscopy and lasing perfomance of Nd3+ doped Ca5(PO4)3F

Absorption and emission spectra and the fluorescence decay of Nd3+ doped Ca5(PO4)3F (FAP) are reported. A slope efficiency of 67% was obtained in pulse operation pumped by a long pulse Cr:LiSAF laser. Diode-laser-pumped lasing of Nd:FAP has been demonstrated for the first time. A slope efficiency of 25% was obtained without any optimization.

Spectroscopy and lasing performance of Nd:KLiYF5 and KLiGdF5

Polarized spectroscopic studies are reported of Nd3+ doped KLiYF5 and Nd3+ doped KLiGdF5--a new anisotropic mixed fluoride. Emission in the 4F3/2 yields 4I11/2 channel is strongly polarized. Explanations of the spectroscopic behavior are presented in terms of the local rare earth environment. Lifetime measurements of the 4F3/2 state of Nd3+ ions in these monoclinic hosts and the dependence of fluorescence lifetime on dopant ion concentration are reported. Low threshold pulsed laser action was realized in both hosts with high efficiency, pumping with a long pulse Cr:LiSAF laser tuned to 797 nm.

Spectroscopy of Yb,Ho codoped KYF4 and its application as upconversion green laser

Detailed room temperature absorption and emission spectra and the dynamics of the upconversion energy transfer were investigated in Yb, Ho codoped KYF4. It was found, in the concentration range studied, that the energy transfer rate from Yb3+ to Ho3+ ions is linearly dependent on Ho3+ concentration. The back transfer from Ho3+ to Yb3+ ions was demonstrated and the transfer rate was found to be superlinearly dependent on Yb3+ concentration. Discussions are presented on the optimization of Yb3+ and Ho3+ concentrations for the potential use of Yb, Ho codoped KYF4 as an upconversion green laser.

Spectroscopy and lasing performance of a new solid state laser crystal--Nd:GdLiF4

Laser action of Nd3+ doped GdLiF4 (GLF) has been demonstrated for the first time for both pulsed and CW laser pumped operation. A slope efficiency of 60% was obtained in either manner of operation. Detailed comparison studies show that the spectroscopic properties and laser performance of Nd:GLF are very similar to those of Nd:YLF. GLF, on the other hand, can be doped with much higher Nd3+ concentration.