%0 Journal Article
%T High-Purity Nanopowders for Laser Applications
%A Deepak Ganta
%A Ganesh Venugopal
%A Andrew T. Hunt
%A Michael Sapp
%J ISRN Nanotechnology
%D 2012
%R 10.5402/2012/608756
%X We have successfully developed high-quality laser-grade yttrium aluminum garnet (YAG), and lutetium oxide (Lu2O3), using a novel combustion chemical vapor condensation (CCVC) technique based on a proprietary NanoSpray Combustion process. The purity of the nanopowders was >99%. Nanopowders with different dopants have been synthesized over a 10¨C200£¿nm size range, with low-cost, high-purity precursors that are viable for large-scale production. Great strides have also been made in developing highly dense (>99% theoretical density) polycrystalline Nd-doped YAG pellets using vacuum sintering and hot isostatic pressing (HIP). This method is an alternative to the Czochralski method for making single-crystal ceramic bodies, which has several disadvantages including high cost, size, shape restrictions, and limitations in Nd concentrations (~1 at %). Nanomaterials also enable higher percentages of Nd to be incorporated into the YAG lattice which improves laser efficiency and >85% near IR transmission, thereby reducing scattering losses associated with larger grain-size polycrystalline materials. 1. Introduction In a little over a decade, ceramic-laser hosts have proven themselves as being a promising option for enabling high-power solid-state laser systems at significantly lower costs compared to single-crystal gain medium. Yttrium aluminum garnet (YAG) has emerged as the most widely produced laser gain host and has enjoyed popularity as a substrate material for optical components. The YAG host is a stable compound, mechanically robust, physically hard, optically isotropic, and transparent from below 300£¿nm to beyond 4 microns. The industry-standard Czochralski process, while successful for making single crystal materials like (YAG), is very expensive and energy intensive as it needs the raw material to be heated to temperature above the melting point of the material (typically ¡Ý2000¡ãC) [1]. The single crystals are also limited in terms of the size and shape that they can be formed in [2]. In addition, solubility of rare earth dopants in some single crystals is limited because of segregation of the dopants. For example, the solubility of Nd is limited to 1 at % in YAG single crystals during growth [3]. Thus, efficient absorption of the excitation is limited, and it is difficult to fabricate a high-efficiency and high-power laser even with the maximum size of single crystals available [4]. On the other hand, polycrystalline ceramic laser materials can be fabricated at relatively low temperatures (<1800¡ãC) and are only limited in size by the sintering ovens that
%U http://www.hindawi.com/journals/isrn.nanotechnology/2012/608756/