Development of Far-Infrared-Transmitting Te Based Glasses Suitable for Carbon Dioxide Detection and Space Optics
By Allison A. Wilhelm, Catherine Boussard-Plédel, Quentin Coulombier, Jacques Lucas, Bruno Bureau, and Pierre Lucas*
The ability to detect and analyze carbon dioxide has become increasingly important in environmental as well as planetary science. Accurate detection of CO2 in the earth’s atmosphere is critical for the study of environmental processes such as global warming and has also recently gained special interest in the field of extraterrestrial exploration because CO2 is produced by living organisms and is therefore regarded as one of the markers of potential life on telluric exoplanets.[1] Remote optical detection of CO2 involves monitoring of its two vibrational absorption bands at 4 lm and 16 lm and therefore requires advanced infrared technologies.[2] Candidate materials for these types of technologies must fulfill three requirements: first, an exceedingly wide transparency window in the far infrared for optical collection; second, good rheological properties for elaboration into various and complex geometries such as micro structured fibers and molded lenses; and third, good chemical stability such as resistance to corrosion in air. Here, we report the synthesis of a new family of glassy tellurides that fulfill these three requirements and could therefore enable the development of a new generation of infrared systems. These glasses which result from the combination of Te with Ge and I exhibit a large optical window extending from 2 lm to 22 lm while being stable enough towards crystallization to permit the preparation of fibers and molded lenses. This is, to our knowledge, the only glass family, which simultaneously shows high stability versus crystallization, chemical durability and an exceptionally large optical transmitting domain. Space programs such as the Darwin mission conducted by the European Space Agency (ESA) or Terrestrial Planet