Segmented cladding fibers for the middle infrared

We report the design, fabrication and optical characterization of total internal reflection segmented-cladding fibers for the middle-infrared spectral range 2-20 μm. Segmented cladding is a novel fiber design in which the uniform core of high refractive material is surrounded by a cladding of alternating segments of high and low refractive indices. Segmented cladding fibers are capable of maintaining a single-mode operation over a wide spectral range with a large core area. The design of the fibers and the simulations were made using the radial effective index method. The fibers were extruded from silver-halide crystals by using the 'rod in tube' method. Using this method we were able to construct large core fibers which exhibited few-modes and relatively low losses at 10.6 μm.