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High-Efficiency, High-Temperature Laser Diodes for Naval High-Energy Laser
Navy SBIR 2012.1 - Topic N121-013 NAVAIR - Ms. Donna Moore - navair.sbir@navy.mil Opens: December 12, 2011 - Closes: January 11, 2012 N121-013 TITLE: High-Efficiency, High-Temperature Laser Diodes for Naval High-Energy Laser TECHNOLOGY AREAS: Air Platform, Sensors, Electronics, Battlespace ACQUISITION PROGRAM: PMA 242 RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted". The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected. OBJECTIVE: Develop and fabricate laser diodes that operate at high efficiencies and temperatures so that the solid-state fiber laser systems into which they are incorporated can meet the stringent size and weight constraints imposed for use on current state-of-the-art tactical air platforms. DESCRIPTION: A vital need exists for a fieldable laser weapon system for use on advanced tactical air platforms. Recent developments in fiber lasers have made doing so feasible. However, stringent size and weight requirements preclude integrating current state-of-the-art high-energy lasers onto fast-moving aircraft. One means to meet those criteria is to reduce the size and weight of the prime power and thermal management systems (TMS) by improving the efficiency and increasing the operating temperature of the laser diode pumps. For example, a current state-of-the-art 50-kW fiber laser system typically has an overall efficiency of approximately 33 percent when incorporating pump diodes having an electrical–optical efficiency of approximately 50 percent. Therefore, this notional system requires >150 kW of prime power, 100 kW of which must be dissipated via the thermal management system (TMS). However, if the diode efficiency can be improved to approximately 80 percent, the total power needed will be reduced by one-third, to only approximately 105 kW. As a direct result, the thermal load decreases almost by half, to approximately 55 kW. As such, the TMS would not have to dissipate as much heat and, thus, could be smaller and weigh less. Furthermore, if the pump diodes could operate at significantly elevated temperatures (70 degrees Celcius to 80 degrees Celsius rather than 50 degrees Celsius), the level of cooling required by the TMS would be substantially reduced. Again, that system’s size and weight could be appreciably less than those utilized in laser weapon systems incorporating current pump diode technology. The expectation for this SBIR is that the diode developed will afford a minimum electrical-to-fiber-coupled optical efficiency of 65 percent. However, the desired level is 70 percent. In addition, the diode must operate effectively at a temperature of at least 70 degrees Celsius (preferably 80 degrees Celsius). For compatibility with high-energy fiber laser systems under development, the diode output must be at a wavelength near 975 nanometers and must be coupled into an optical fiber suitable for standard fusion splicing with typical gain fibers. The device’s life span must be in excess of 5,000 hours. In addition, the criterion for the minimum number of watts per diode package is 50. The ability of the diode to successfully withstand the severe conditions to which it will be exposed when deployed is essential. Therefore, the device must pass pertinent shock, vibration, and temperature environmental testing. The diode must be designed in a way to be competitive with industry state-of-the-art high-volume manufacturing practices (on a dollar-to-watt basis). For instance, the goal for the end of the program is a cost of less than $5 per watt. Successfully satisfying these challenging objectives will require an enormous degree of both innovation and creativity. PHASE I: Develop a conceptual design for a laser diode that operates at the specified efficiencies and temperatures, and satisfies the other criteria presented herein. Include the methodology adopted, and prove feasibility of a prototype that will meet performance objectives. PHASE II: Devise detailed designs for the concept developed in Phase I and fabricate a limited number of diodes suitable for proof-of-concept testing. Conduct preliminary assessments in a laboratory setting and in government-owned laser resonators and document the results. PHASE III: Scale up for mass production of the advanced laser diodes. These devices, upon meeting Navy requirements, will be transitioned to various laser programs. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: These devices have significant commercial potential in components for laser systems used in large-area displays, medical equipment, and semiconductor/lithography systems. In addition, these cutting-edge diodes have applications that are integral to the communication industry. The suggestion is to team with a fiber laser developer because these diodes will be a major component in their laser systems. REFERENCES: 2. Kamuz, A. M., Oleksenko, P. F., Ovsyannikov, E. Y., Sizov, F. F., & Dyachenko, T. A. (1996). Low-temperature photo-hydro-modification of II–VI and III–V semiconductors. Applied Surface Science, 103(2), 141-148. doi: 10.1016/0169-4332(96)00111-0 3. Krivoshlykov, S. G. (1999). U.S. Patent No. 5,909,614. Washington, DC: U.S. Patent and Trademark Office. 4. Pankove, J. I (1971). Optical processes in semiconductors. New York: Dover Publications, Inc. KEYWORDS: Laser Radar, Laser Diodes, High-Efficiency Diodes, High-Temperature Diodes, High-Energy Laser, Electrical–Optical Efficiency, Laser Weapon Systems
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