Sulfide, selenide and telluride glass fibers were prepared for infrared optical applications. A new crucible drawing method was developed for the drawing of fibers with glass cladding. The extrinsic losses caused by some oxide impurities were suppressed by the purification of raw elements. The transmission loss and mechanical strength, i.e., bending and tensile, of each fiber were investigated before and after the heat treatment under humid conditions. The fibers obtained were used for the power delivery of CO 2 laser (10.6 μm) and CO laser (5.4 μm). The antireflection coating onto fiber ends and cooling of fiber with gas or water were examined for the improvement of power transmission efficiency. A fiber cable having ZnSe lens at the output end was prepared for medical and other applications. Temperature monitoring, thermal imaging and gas sensing were also tried using the fibers.