Low-Loss ZBLAN Glass and Fiber Fabrication in Low Gravity

ABSTRACT: Real-time spectral signature recording and identification of satellites is an essential need of the Ground-based Electro-Optical Deep Space Surveillance (GEODSS) system. The Air Force is seeking a low-loss ZBLAN fiber (ZrF4-BaF2-LaF3-AlF3-NaF composition) with wide spectral band optical transmission for satellite tracking systems. Expanding the detection range from the ultraviolet to the mid-infrared wavelengths can substantially improve the satellite spectral identification. ZBLAN glass compositions, however, have high loss due to crystallization when fabricated on Earth. To address this Air Force need for low-loss ZBLAN glasses and optical fibers, Physical Optics Corporation (POC) proposes to prepare and conduct a ZBLAN fiber drawing experiment in low gravity on a Black Brand V type sounding rocket payload. An additional experiment with a similar ZBLAN glass host that is highly doped with active ions for laser applications will help to answer the question of whether crystallization of the perspective glass compositions could be suppressed enough to meet the low loss requirements for countermeasure applications when processed in low gravity. This Phase II project execution will utilize the available standard payload designs and will closely follow the established NASA program schedule for sounding rocket missions. BENEFIT: Through the confirmation of crystallization suppression in low gravity during fiber fabrication, the mission will open a pathway toward a unique opportunity to substantially expand the range of applicable fiber material compositions. Such compositions, including highly doped ZBLAN glasses with theoretical insertion loss orders of magnitude lower than in existing fibers, would enable high-power mid-infrared (mid-IR) lasers for a variety of DoD and civilian applications, including countermeasures, wideband hyperspectral imaging, industrial plastics processing, and medical laser treatment.