Evaluation of Ho:KPb2Cl5 as a Diode-Pumpable Mid-IR Laser Material
ARMY RESEARCH LAB ADELPHI MD ADELPHI United States
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We have investigated several room-temperature spectroscopic properties of a recently grown crystal of holmium HoKPb2Cl5, to evaluate its potential as a diode-pumped mid-IR laser material. We have measured its absorption and fluorescence spectra, and the fluorescence lifetimes of several excited states. These have enabled estimation of the stimulated emission cross section at the 3900-nm peak relevant to laser operation. This crystal shows substantial improvements in lifetime, linewidth, and cross section compared with earlier samples investigated by others, indicative of greatly reduced inhomogeneity. However, very weak absorption in the wavelength range of the most practical laser diodes makes this and any Ho3-doped material very difficult to use as a diode-pumped laser.