Optical characterization of infrared telluride glass fibers for space use

High Tellurium (Te) content chalcogenide glass fibers are considered as candidates for single mode waveguides in the upper wavelength range (10 – 20 μm) of the DARWIN mission. In this paper two methods for IR optical characterization of the Te glass fibers are presented, including (1) a broadband spectral technique using an FTIR spectrophotometer and (2) a CO2 laser set-up for measuring the fiber attenuation at 10.6 μm. In both methods the optical attenuation (in dB/m) of experimental mono index Te glass fibers of around 500 μm diameter has been determined by applying the fiber cut-back technique. Some typical results of both methods for a few different types of high Te-glass fibers will be shown. Since Te-glasses are semiconducting materials, the optical properties of Te-glass fibers strongly depend on temperature. Preliminary low temperature measuring results confirm the beneficial effect of cooling on the transmission of high Te glass fibers.