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International audienceThe Dy3+ doped Ga5Ge20Sb10S65 bulk glass provides good emission efficiency in the middle IR with a better brightness than the blackbody sources. Sulfide single index fibers doped with Dy3+ (500-​3000 ppm) were drawn with optical attenuation of about 1-​3 dB​/m, suitable to develop fluorescence sources for chem. anal. by optical absorption in middle IR. They particularly present a broad emission around 4-​5 μm, making them attractive for CO2 detection. Considering the low cost and efficient Dy3+ pumping scheme by means of a com. laser diode, the Dy3+ sulfide fiber reveals potential for developing a CO2 optical sensor. Using the 4.35 μm broad emission of a Dy3+ doped Ga5Ge20Sb10S65 fiber combined with a differential measurement technique, the CO2 gas concn. measurement was carried out fruitfully. For this specific application, the CO2 detection threshold was fixed at about 400 ppm corresponding to atm. concn. and was successfully reached for a cell length of 1.5 cm with a resoln. of about 5​%. The sensitivity of the setup is mainly related to the size of the cell, deliberately reduced to develop a robust and compact system for natural geol. sites

Physical properties, including mechanical, thermal and optical properties, have been investigated for chalcogenide glasses in the Ge x Se 1-x system, for x ranging between 0 and 0.42. In the 0=2.4). Conversely, the chemical threshold (=2.67) clearly induces a change in the compositional trend of these properties. In the x>1/3 range, T g decreases and the elastic moduli markedly increase, which is not expected from the continuously reticulated model. The change of the physical properties in this range is an indicator of the existence of separated Ge-rich domains.

Microstructured optical fibers (MOFs) are traditionally prepared using the stack and draw technique. In order to avoid the interfaces problems observed in chalcogenide glasses, we have developed a new casting method to prepare the chalcogenide preform. This method allows to reach optical losses around 0.4 dB/m at 1.55 µm and less than 0.05 dB/m in the mid IR. Various As(38)Se(62) chalcogenide microstructured fibers have been prepared in order to combine large non linear index of these glasses with the mode control offered by MOF structures. Small core fibers have been drawn to enhance the non linearities. In one of these, three Stokes order have been generated by Raman scattering in a suspended core MOF pumped at 1995 nm.