Abstract

Since 1975, several researchers, including Dianov, Miyashita, LeSargent, Harrington, Hartouni, and Bornstein, have been working on IR transmitting fiber optics for the far-IR (8-12-μm) spectral range. Numerous possible applications are discussed in several articles. The work reported to date has been divided between polycrystalline materials, such as KRS-5 and AgCl, and amorphous materials, such as AS₂S₃ and GeAsSe glasses, with a small amount of work done by Israel in Ge₂₈Sb₁₂Se₆₀ (TI 1173 glass). Polycrystalline fibers, having absorption levels of <1 dB/m at 10.6 μm, have never been successfully clad by any research group and suffer from several problems such as low strength, thermal instability, aging effects, restrictions on minimum fiber diameters, and the potential for permanent deformation during bending. Chalcogenide glass fibers have been clad using the rod-in-tube approach and the double- crucibte method but have higher absorption levels than do polycrystailine fibers. No one since Kapany (late 1960s) has reported producing anything other than single-fiber products for the far-IR region.

© 1985 Optical Society of America