Air-cooled High-power Blue-Green Laser

The United States Navy currently is developing airborne mine detection systems (AN/AES-1) that use laser illumination coupled with sensitive electro-optic receivers to find mines in the upper part of the water column. Although the equipment is intended for operation from a manned helicopter, the next generation of such equipment is expected to operate from unmanned aerial vehicles (UAVs). Such platforms are anticipated to provide less payload and power than is available from the current helicopter platform. The single biggest subsystem in terms of weight and power consumption in the current system is the laser and its associated environmental conditioning equipment (ECS). Therefore, we propose to evaluate novel laser design concepts that incorporate: a high-temperature diode pumping (optimized for 50 degrees C or more); an efficient pump head design with optimum coupling to the matching solid-state laser media; distributed thermal load design; efficient and high beam quality cavity; and solid-state frequency doubling to produce 500-540 nm blue-green laser output. The theoretical design including distributed thermal management and the blue-green laser output performance will be predicted using commercially proven modeling software. During Phase I, based on the theoretical modeling, we propose to design, develop and test a proof-of-principle high-temperature, limited energy diode-pumped solid-state laser oscillator head, a scaled down thermoelectric (TE) cooling array, an optimized fin air-to-air heat exchanger platform for the limited energy oscillator as well as scaled down water-to-air heat exchanger and heat distributor/regulator subassemblies. The test data collected will allow fine tuning of the theoretical software models and will assure the scalability of the Phase I design models to support Phase II and Phase III laser system requirements. The finalized Phase I design concept and the theoretical modeling will first support the design, development and production of the Phase II prototype laser system. Phase I program results and validated theoretical modeling for the design should allow the Phase II laser system to have at least 4 watts of 500-540 nm output, at a pulse repetition rate suitable for meeting present AN/AES-1 technology insertion requirements of 100-400 Hz. Additionally, the Phase II laser system will meet all safety criteria established in ANSI Z136.1-2000 for military exempt lasers. Laboratory demonstration of this complete laser system will be structured to demonstrate full functionality over the intended temperature range of 0-120 degrees F (-18 to 49 degrees C). During Phase I and Phase II, additional theoretical software models will be developed for the design and development of a larger scale amplifier network which will show how the developed technology can be scaled to 40 watts of blue-green output at higher pulse repetition rates of up to 400 Hz, suitable for meeting AN/AES-1 technology insertion requirements. Although diode-pumped lasers with the properties described above have been demonstrated for R&D and limited commercial applications, considerable development is especially required to build the robust systems that would be needed for the Phase III effort to include the laser as a P3I replacement for the current laser in the AN/AES-1, and/or for the follow-on program for operating an AN/AES-1 capability from a UAV. Our SBIR Phase I proposal incorporates all state-of-the art laser and thermal management technologies and it is intended for design, development and production of a solid-state blue-green laser that can meet the needs of such air-cooled blue-green laser system requirements of the United States Navy.