Chalcogenide glasses are known for their large transparency in the mid-infrared and their high refractive index (>2).
They present also a high non-linear coefficient (n2), 100 to 1000 times larger than for silica, depending on the
composition. An original way to obtain single-mode fibers is to design microstructured optical fibers (MOFs). These
fibers present unique optical properties thanks to the high degree of freedom in the design of their geometrical structure.
A classical method to realize MOFs is the stack-and-draw technique. However, with chalcogenide glasses, that technique
induces optical losses at the interfaces in the stack of capillaries. In consequence, we have developed a new casting
method to fabricate the chalcogenide preform. This method permits to obtain optical losses around 1 dB/m at 1.55 μm
and 0.3 dB/m in the mid-IR region. Various chalcogenide microstructured fibers working in the IR range were prepared
in order to take advantage of the non-linear properties of these glasses and of the original MOF properties. For example,
fibers with small effective mode area (Aeff < 10 μm2) have been realized to exacerbate the non-linear optical properties.
Such fibers will find applications for signal regeneration in telecom, and for the generation of supercontinuum sources.
On the contrary, for military applications in the 3-5 and 8-12 μm windows, large effective mode area and single mode
fibers have been designed to permit the propagation of high-power gaussian laser beams.