Single-mode microstructured optical fiber for the middle infrared

Microstructured crystalline optical fiber from silver halides is described. Both experimental and theoretical evidences are presented to establish that the fiber is effectively single mode at wavelength 10.6 mu m with numerical aperture NA=0.16 and optical losses of similar to 2 dB/m. Crystalline microstructured optical fibers offer key advantages over step-index optical fibers from silver halide crystals. The wide transmission range of wavelengths 2-20 mu m provides great potential for applications in spectroscopy and for the development of a range of new crystalline-based nonlinear optical fibers. (c) 2007 Optical Society of America.