This Small Business Innovation Research (SBIR) Phase I project seeks to develop a method for the production of polycrystalline YAG laser gain media containing gradients of dopant in either linear or radial directions within the part. Such parts offer performance improvements for both output power and beam quality in diode pumped laser systems manufactured by commercial laser vendors. No commercial supplier of such components exists today. A technique based on deposition of thin layers of doped and undoped YAG nanopowder slurries stacked on top of one another to build up part thickness will be developed. Parts containing continuous (not step-wise) dopant gradients over distances up to one centimeter will be demonstrated, representing parts larger than those demonstrated in literature to date. Primary Phase I objectives include generation of uniform thickness layers to allow growth of uniform, thick parts, drying of slurry layers to produce crack free green bodies, and demonstration of high optical quality components containing prescribed doping profiles. Successful completion of the development will establish the capability to supply laser gain media containing dopant profiles to the commercial market, allowing substantial improvement in commercial diode pumped lasers with minimal modification of existing system architecture.
The broader impact/commercial potential of this project stems primarily from the laser performance improvements that will be enabled by successful development of graded doping profiles in YAG based laser gain media. Graded doping profiles improve both maximum output power and beam quality of diode pumped solid state lasers. Such lasers are used in applications including laser cutting and welding, processing of electronics and photovoltaics, and laser sensing systems. Improvements made to these systems enable efficient domestic manufacturing in a cost competitive manner with respect to offshore manufacturing. Development of cutting edge manufacturing technologies is therefore key to re-establishing the US manufacturing base in the world market.
The purpose of this work was to demonstrate proof of concept for a new method of manufacturing ceramic laser parts that contain gradual changes in composition from one end of the piece to the other. Industrial lasers used for cutting, welding, semiconductor manufacturing, and marking applications can use such parts to operate at higher powers and to generate laser beams that can be focused with less distortions, improving the products made using these manufacturing techniques. A significant advantage of this technology is that it is a drop-in component to enhance performance of existing systems; very little re-engineering of existing industrial lasers has to be done to use the new technology. As part of this program, a new ceramic manufacturing technique based on spray deposition of thin layers, similar to building up layers of paint on top of one another, was demonstrated. We believe that this work represents the first use of such techniques for the commercial manufacture of optical ceramic parts. Methods to characterize the compositional variation produced were established, and part specifications of interest to laser manufacturers were identified. Parts containing specific compositional variation were produced and are being tested for performance enhancements by leading industrial laser manufacturers. It is hoped that further refinement of the techniques developed during this program will yield a commercial supply of next generation laser components for improved laser manufacturing.
