Optical and laser characterization of Nd:YAG ceramics elements

Abstract

ABSTRACT The Nd:YAG ceramics of nominal 1% and 2% Nd dopant were produced by a solid-state reaction of high-purity (4N) nanometric oxides powders i.e. Al 2 O 3 , Y 2 O 3 and Nd 2 O 3 . Yttrium oxide nanopowder (XRD crystallite size of 79 nm) was produced by precipitation from water solution of high-purity hydrated nitrate, by means of ammonia hydro-carbonate. The cold isostatic pressing method was applied to densify granulated powder. Further the sintering and annealing processes were deployed to produce the final Nd:YAG ceramic samples. Mean grain sizes of about 20 P m and grain boundaries less than 10 nm of elaborated Nd:YAG ceramic samples were evalua ted in SEM and TEM measurements. Thus, in microscale the quality of obtained ceramic was quite satis factory. However, in macr oscale, the samples had unacceptable level of voids and pores observed in visual inspection, which resulted in low 76% transmission, corresponding to extinction coefficient of 0.32 cm -1 at 1064-nm wavelength. The sizes of defects, pores and inclusions were of several dozens of micrometer. The active elements of rod and slab shape were fabricated and ch aracterized in two diode pumping laser set ups. In end pumping configuration as a pump source 20-W fiber coupled laser diode was deployed. For the low duty cycle pumping (1 ms/20 Hz) above 30% slope efficiency was achieved. In the best case, 3.7 W of output power for 18 W of pump power, with M