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Improved Optical Filters to Support Submarine Optical Communications Links
Navy SBIR 2009.1 - Topic N091-067 ONR - Mrs. Tracy Frost - [email protected] Opens: December 8, 2008 - Closes: January 14, 2009 N091-067 TITLE: Improved Optical Filters to Support Submarine Optical Communications Links TECHNOLOGY AREAS: Information Systems, Electronics ACQUISITION PROGRAM: Submarine Integration Program Office (PMW-770), Comms at Speed and Depth OBJECTIVE: Optical filters that complement the proposed development of submarine blue-green lasers for communications at speed and depth. DESCRIPTION: The 450 to 550 nm blue-green wavelength region, and in particular the center 50-nm band within this region, is attractive for underwater communications and submarines communications at speed and depth across the water-air interface. This is because optical propagation loss is minimized, given the quality (Jerlov characteristics) of water, at blue wavelengths for deep ocean and green wavelengths for coastal waters. Additionally, certain wavelengths within the blue-green region, such as 486 nm and 518 nm, correspond with Fraunhofer absorption lines that have a 5 to 17 dB reduction in solar optical noise [1], so operating at these wavelengths may provide additional link margin during daytime operation. Earlier, optical filter development at 532 nm was pursued in response to ready availability of laser sources at 532 nm [2, 3]. Now there is renewed focus on laser development in the bluer regions [4], with a high probability of achieving suitable laser pulse powers at 486 nm and 518 nm. Clearly, one requires high performance optical filters to match these wavelengths of operation as well. The purpose of this SBIR is to study, design, fabricate, characterize, integrate (with receiver/transmitter system) and test wide-angle (90 degrees field of view), narrowband (a transmission peak full width at half maximum of less than one nanometer at the desired wavelength) optical filters for the 486-nm and/or the 518-nm wavelengths, with a clear aperture diameter preferably greater than one inch [2], with scalability to larger apertures. Atomic resonance filters, for example, are able to meet these specifications [3, 5, 6]. Additionally, while challenging, it is a desire to have the optical filter be capable of being 'configured' (not necessarily actively tuned) or modified for use at any wavelength in the 450-550 nm span. PHASE I: Study � to include modeling and laboratory experimentation � and design a filter capable of meeting all of the objective requirements. Key elements of the filter should be built and their performance demonstrated. PHASE II: Develop, test and deliver � as specified by the government � a prototype filter meeting all objective requirements. PHASE III: Test air-to-undersea laser link after integrating the prototype receiver into a submarine or submerged platform. Design, construction, characterization, and testing of the system will be performed jointly by the Department of the Navy and integration contractor. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Underwater high data rate communications could be beneficial in transmission of data (e.g. video) between commercial platforms where at least one of the platforms is located underwater. REFERENCES: 2. SBIR N06-095, Optical Filter for Undersea Blue-Green Laser Communications. 3. John D. Feichtner, Satellite to Submarine Laser Communications (SLC)-Advanced Filter Technology, Lockheed Missiles and Space Company, P000187R, January 1992 4. Office of Naval Research Broad Area Announcement 08-008. 5. Jerry A. Gelbwachs, "Atomic Resonance Filters", IEEE Journal of Quantum Electronics 21, 7, 1266 (1988). 6. J.A. Gelbwachs and M.D. Tabat, "Solar background rejection by a pressue-broadened atomic resonance filter operating at a Fraunhofer wavelength", Optics Letters 14, 4, 211 (1989) KEYWORDS: Laser; Communications; Optical; Filter; Blue-Green; Submarine
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