99--TECHNOLOGY TRANSFER OPPORTUNITY THIN-FILM EVAPORATIVE COOLING FORSIDE-PUMPED LASERS OFFERS IMPROVED MONOCHROMATICITY AND OPTICAL EFFICIENCY

NASA Langley Research Center in Hampton, VA solicits inquiries from companies interested in obtaining license rights to commercialize, manufacture and market the following technology. License rights may be issued on an exclusive or nonexclusive basis and may include specific fields of use. NASA provides no funding in conjunction with these potential licenses. THE TECHNOLOGY: Scientists at NASA Langley Research Center have developed novel NASA technology to improve upon current water- and ammonia-based conductive cooling systems for optically pumped solid-state laser crystals. NASA is developing 2.0-micron LIDAR lasers, which employ solid-state laser crystal rods that are optically pumped from the sides using diode lasers positioned around the circumference of the crystal. Optically pumping the crystal creates a high heat flux within the crystal. Current conductive cooling of these pumped crystal lasers is inadequate to uniformly address the generated heat flux, which can result in poor optical performance and even thermal damage to the crystal. Water-cooling can uniformly cool the laser crystal but provides only room temperature cooling, which results in poor optical output efficiencies in the laser. Ammonia-based coolants offer a much lower cooling temperature but do not provide uniform cooling throughout the laser crystals, which results in uneven cooling within the crystal. This lack of uniform cooling results in reduced monochromatic output of the laser light. In addition, water and ammonia cooling approaches add packaging complexity. The technology described here overcomes the drawbacks of traditional conductive cooling approaches using a unique evaporative cooling technique. The NASA patent-pending design includes a transparent cylindrical housing that surrounds the solid-state crystal rod, creating an annular gap along the length of the rod. A suitable, common cooling fluid is injected into the gap so that the coolant liquid wets the rods surface in a thin film layer. This thin film is critical to ensure that the cooling fluid does not boil, but instead undergoes a controlled evaporative phase change from liquid to gas. With sufficient space between the thin-film cooling layer and the transparent housing, the coolant can continuously evaporate into the space without boiling and provide highly efficient cooling along the length of the rod and across its radial profile. The resulting cooling is more uniform and efficient than conductive cooling approaches, and the DPSSL packaging is simplified. Modeling the effects of evaporative cooling indicates that the NASA technique is significantly more uniform and enables higher optical output than traditional cooling methods. To express interest in this opportunity, please respond to contact@example.gov with the title of this Technology Transfer Opportunity as listed in this FBO notice and your preferred contact information. Please also provide the nature of your interest in the technology along with a brief background of your company. For more information about licensing other NASA-developed technologies, please visit the NASA Technology Transfer Portal at http://technology.nasa.gov/ . These responses are provided to members of NASA Langleys Office of Strategic Analysis and Business Development OSACB for the purpose of promoting public awareness of NASA-developed technology products, and conducting preliminary market research to determine public interest in and potential for future licensing opportunities. If direct licensing interest results from this posting, OSACB will follow the required formal licensing process of posting in the Federal Register. No follow-on procurement is expected to result from responses to this Notice.