Room-temperature lasing at 2.1-microm has been demonstrated in Ho:Lu(3)Al(5)O(12) with a slope efficiency of 82% and a threshold energy of 4.4 mJ. A maximum absorbed energy of 17 mJ yielded 10 mJ of laser output energy. To simulate diode-pumping experiments, a tunable Co:MgF(2) laser operating at 1.878 microm was used to achieve lasing on (5)I(7) ? (5)I(8) transitions.
A diode-pumped, room-temperature Tm:LuAG laser demonstrated a total optical-to-optical efficiency of 0.073 and an optical-to-optical differential efficiency as high as 0.236. Laser performance and operating wavelength were investigated as a function of the Tm concentration. The highest laser output energy was achieved with a Tm concentration of 0.04 and at a wavelength of 2.0238 µm.
Thermally stimulated luminescence from one natural and two synthetic samples of alpha-quartz has been investigated in the range from room temperature to 400 °C. Comparisons were made between unswept samples and others, taken from adjacent positions in the original stones, that were swept in a hydrogen atmosphere. Three sets of thermally stimulated luminescence (TSL) data were obtained from each sample, corresponding to initial electron irradiation at 77 K, at ice-bath temperature, and a double irradiation at ice bath plus 77 K. Electron spin resonance and infrared absorption data also were obtained from the same samples. A number of TSL peaks were found in the 60–130 °C region and they have been tentatively associated with hydrogen in the crystal. More intense peaks were found in the 200–300 °C region, but only in unswept samples after an ice-bath or ice-bath plus 77-K irradiation. These latter peaks are attributed to electron-hole recombination at [AlO4]0 centers as a result of electron release from alkali-associated electron traps.
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