Robust Mid-IR Optical Fibers for Extreme Environments

ABSTRACT: Infrared sources and sensors are becoming increasingly useful for military and commercial applications. We propose to exploit recent advances in multimaterial fiber technology to produce a new class of optical infrared fibers that are robust and low in cost for high-power, high-stress environments. The use of beam confining fiber optics reduces or eliminates issues with misalignment or damage caused by vibration, large temperatures variations, moisture, and g forces - all present in military aircraft. Fibers also provide a practical method of optical power transport from source to application (or window for airborne sensing or countermeasures applications), especially through confined spaces typical of military aircraft. Our fibers make use of chalcogenide glasses that are transparent in the mid-infrared spectrum. By combining chalcogenide glasses with thermoplastic polymers monolithically in the same fiber strand, we produce highly robust fibers made in large quantities with high optical quality, low loss, and low cost. In this Phase I effort, we propose to demonstrate feasibility of these claims in fibers packaged with standard connectors. Such a product will revolutionize how infrared applications are designed and lead to higher volumes of chalcogenide fiber use and lower cost.; BENEFIT: Chalcogenide fiber is of interest for a number of applications including chemical sensing, biological agent detection, laser surgery, medical diagnostics, infrared countermeasures and laser radar. The fiber is often used primarily as an infrared laser power transport medium although nonlinear frequency conversion, modulation and switching are additional uses. Standard silica glass fiber, tellurite fiber, and fluoride fiber do not have the broadband infrared transparency range of chalcogenide fiber. But the high cost and lack of robustness of currently available chalcogenide fiber is inhibiting adoption of this fiber for infrared applications. For example, placing fiber on a military aircraft will require unimpaired performance under extreme vibration and rapid temperature changes over large ranges (−55C to 125C). The fiber must have a high tensile strength throughout this temperature range but it must also endure thousands of flexes at high speeds. Via this research and development program we will produce the robust fiber needed for demanding infrared military applications. Our fabrication technique is also amenable to large scale production of fiber at low cost. Making reliable and robust chalcogenide fiber available at low cost is likely to result in considerably more interest and use in numerous current and future military and commercial applications.