Optical and mechanical properties of single-crystal sapphire optical fibers

Single-crystal sapphire fibers are produced by the laser heated pedestal growth technique. The fibers have attenuation coefficients of less than 2 dB/m at the Er:YAG laser wavelength of 2.94 µm and are used to deliver over 600 mJ of Er:YAG laser energy. Mechanical testing of these fibers and the sapphire fibers produced by the edge-defined, film-fed growth technique results in a measured 0.4% strain to failure when testing is done under a 4-point load. Teflon-FEP (perfluorinated ethylene propylene) is applied to sapphire fibers as a cladding. The cladding is extremely effective in preventing leakage of energy from the fibers into absorbing environments that may surround the fiber.