Investigation on Te-based chalcogenide glasses for far-infrared fiber

Abstract

When infrared (IR) is over 12 m, conventional chalcogenide (ChG) fibers are confused by the multiphonon absorption of Se, and novel glass materials for far-IR have become one of hot research points in recent years. Here, a novel ChG glass and fiber for far-IR without containing Se/As is well investigated. The glasses GeTe-AgI are purified by distillation and synthesized by melt-quenching method. The thermal properties and the infrared transmissions are reported. The step-index fiber, fabricated via a novel extrusion method, exhibits excellent transmission at 8-15 m: 24 dB/m in a range of 8-15 m and 15.6 dB/m at 10.6 m. The influences of oxygen contaminant and the purity of AgI on the glass transmission and fiber attenuation are discussed. Structural and physical properties of GeTe-AgI glass system are studied with differential scanning calorimetry and ellipsometer instrument. Optical spectra of GeTe-AgI glass system are obtained by spectrophotometer and infrared spectrometer. Main purification process with oxygen-getters (magnesium) is disclosed. The fiber attenuation is measured by the cut-back method with a Fourier transform infrared spectrometer. The lowest loss of this fiber can be reduced to 15.6 dB/m at 10.6 m. The results show that these glasses are well transparent in a wide IR window from 1.7 to 25 m, and these glass fibers can transmit light up to 15 m, thus the GeTe-AgI glass system is one of good candidates for far-IR. The fiber attenuation can be reduced effectively by the reasonable purification and novel extruded-processing. These environment friendly fibers are suited for far-IR applications, such as greenhouse gas sensing and the power delivery of CO2 laser.