Proceedings PaperPanel Discussion: The Future In Infrared Fibers
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DeShazer: During this meeting, IR fibers have been viewed from two aspects - materials and applications. We have had an interesting mix of chemists and physicists, engineers and opticians attending the meeting because of the varied expertise needed to address these questions. While silica glasses are exclusively used for current fiber systems operating at wavelengths less than 2 μm, the material choice has not yet been made for IR fibers at the longer wavelengths. Papers were presented at this meeting on the possible choices, which can be grouped into four general headings, as we have done in the table: hollow waveguides, glasses, polycrystals, and crystals. For the 2 to 5 μm spectrum, the choice appears to be fluoride glass, although the exact glass composition needs to be determined for good fiber drawing properties. For wavelengths longer than 5 μm, however, there is no unanimous choice. Polycrystalline KRS-5 fiber has been the current selection for CO2 laser fiber systems at 10.6 μm, but it exhibits many drawbacks such as large scattering loss, short shelf-life and possible photosensitivity. Chalcogenide glasses, such as arsenic triselenide, have high absorption losses at 10.6 μm, in spite of much past effort to improve the material. Is there hope in producing a highly transparent glass at 10.6 μm? If not chalcogenide glasses, maybe chloride glasses will succeed for fibers at 10 μm. Single-crystal fibers promise low loss, but is it realistic to talk about making a single crystal fiber 10 km long?