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Integrated Fast-light Micro-inertial Sensors for GPS Denied Navigation


OBJECTIVE: To demonstrate technology leading to an integrated approach to optically pumped atomic gyro/accelerometers with 1000X improvement in sensitivity. DESCRIPTION: The Air Force is developing advanced technologies leading to small compact systems, which need micro-inertial measurement systems far beyond current state of the art. Development of low size, weight and power (SWaP) components that can be used in an Inertial guidance unit that would maintain position location knowledge for long periods of time with only an occasional update from GPS would enhance long term location accuracy stability and provide greater reliability for satellites applications above the GPS constellation. Recent developments have shown gyros, and rate sensors and other instruments based on optically pumping rubidium or cesium using single frequency semiconductor lasers precisely tuned to the atomic resonance transition. These experiments including those using"cold atom"optics have shown great potential but have a long path to small system insertion. Recent experiments with"fast or superluminal light"have shown promising results to provide nearer term insertion with small footprint and an order of magnitude accuracy improvement. Rubidium and cesium devices have shown promise for compact, low SWaP microsystem applications but are a long way from transition into practical, ruggedized 3-axis flight and ground system applications. Basic research experiments as derivatives of chip scale atomic clocks have shown that hybrid integrated optical-fast light devices could potentially have large expensive laser ring gyro performance in sizes as small as 1 cubic centimeter. Ring laser structures with anomalous dispersion (i.e., a fast-light medium) are examples of approaches to realize a rotation sensor with a sensitivity enhanced by a factor as high as 10E5 for experimentally accessible parameters. It may also be possible to use this approach to realize an accelerometer, with a similar enhancement in sensitivity. Given conventional optical accelerometers can achieve a sensitivity of less than 1micro-G/root-Hz, it should thus be possible to reach a sensitivity as high as 10 pico-g/ root-Hz. Furthermore, since the enhancement is non-linear, the device should have a very high dynamic range, and should also be able to sense large accelerations as well. Recent breakthroughs in single frequency semiconductor laser diodes and bidirectional amplifiers have enabled a conceptual integration into a single laser driven multi-axis inertial sensor with sense nodes on sub-centimeter cubed scale. Miniaturized, frequency-agile, robust laser systems that can operate autonomously while locked to atomic transitions with prescribed offsets up to 10 GHz are also needed. These lasers are marginally available today from an offshore supplier, but DoD users and other contacts report long delivery times, low reliability, and frequent failure to meet published specifications. Emerging domestic suppliers must be developed to ensure stable sources of supply of these precision lasers. The SBIR topic solicits novel concepts and component technologies in design, development, and demonstration of components, subsystems, and systems for an integrated fast light optical device atomic/quantum 3 axis transducer for rotational and linear inertial sensing (Inertial Measurement Units), and replacement of digital compasses. The sensing system should be able to withstand the space environment, acceleration, and vibration environments of launch and be able to have long term endurance for orbital environments (300kRad Si Gamma, 300kRad Proton @63MeV) Original author Schmieder, Shirley [Ms.] (RW), PHASE I: Conduct experimental and analytical efforts to demonstrate proof-of-principle of the proposed technology and concept. Determine expected performance through extensive analysis/modeling effort. Identify technical risks and develop a risk mitigation plan. Investigate integration of lasers, modulators and environments PHASE II: Design, develop, and characterize prototypes of the proposed technologies and demonstrate functionality. Demonstrate feasibility and engineering scale-up of proposed technology; identify and address technological hurdles. Demonstrate applicability to both aircraft andspacecraft environments, including vacuum, cryogenic operation, and long term radiation exposure. PHASE III: Military App: Provide an inertial reference for small spacecraft at GEO for which GPS signals may not be available. Commercial App: Develop manufacture the micro-optical atomic inertial , subsystem or system developed in PHASE II. Incorporate on Commercial satellites to reduce power and weight. REFERENCES: 1. New Innovations in Chip Scale Atomic Clocks (CSAC), Honeywell Inc. Fact Sheet, & page=aerotechmagazinearchive3_two & theme=T4 & catID=CAJGEVG59TXDA5SO8CM5CU9WUV3N2ZISW & id=HHOI131WCWZ6DPPWJT4KBLDJMFPKZ5GAJ & sel=3 2. M.A. Perez, U. Nguyen, S. Knappe, E. Donley, J. Kitching and A.M. Shkel,"Rubidium Vapor Cellwith Integrated Nonmetallic Multilayer Reflectors", 3. P. D. D. Schwindt, L. Hollberg, and J. Kitching,"Self-oscillating rubidium magnetometer using nonlinear magneto-optical rotation", REVIEW OF SCIENTIFIC INSTRUMENTS 76, 126103 , 2005. 4. Achtenhagen, M., Amarasinghe, N.V., and Evans, G.A.:"High-power distributed Bragg reflector lasers operating at 1065 nm", Electron. Lett., 2007, 43, (14), pp. 757759. 5. Jekeli C.,"Inertial Navigation Systems with Geodetic Applications", de Gruyter
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