Processing and optical properties of YAG-and rare-earth-aluminum oxide-composition glass fibers

摘要

Rare-earth-aluminum oxide-composition glass fibers 5-50 mum in diameter and containing up to 50 mole% rare-each oxide were drawn from undercooled liquids 550-650K below the equilibrium melting point.The fibers have tensile strengths of approx6 GPa,glass transition temperatures of approx1150K,and infrared transmission up to approx5500nm.The optical properties of erbium-doped fibers containing up to 12.5 mole% Er_2O_3 were investigated.The 1/e lifetime of the ~4I_(13/2) excited state was 0.8-7ms,decreasing with increasing Er concentration.Amplified spontaneous emission measurements indicate extremely broadband spectra,up to 135 nm (3-dB width) in 0.5mole% fibers.Although this result is encouraging,the gain bandwidth,which has not been measured,is likely narrower.Glass fibers were crystallized by heat treatment under tension at temperatures of 1300-1900K to form flexible,creep resistant polycrystalline monofilaments with tensile strengths up to 2.4 GPa.