Chalcogenide glass fibers for mid-infrared transmission

Chalcogenide glass fibers for mid-infrared transmission have been fabricated in As-S, As-Ge-Se, and Ge-S glass systems using high purity materials. The preparation of unclad, Teflon FEP clad, and chalcogenide glass clad fibers and their transmission loss characteristics are reported. It is found that appropriate glass compositions for drawing low-loss fibers are limited to the narrow ranges in the glass-forming regions. The minimum losses obtained are 35 dB/km at 2.44μm for As40S60unclad fiber, 182 dB/km at 2.12 μm for As38Ge5Se57unclad fiber, and 148 dB/km at 1.68 μm for Ge20S80unclad fiber. It is shown that hydrogen impurity absorptions and short-wavelength weak absorption tails seriously enhance loss in the fibers. It is also suggested that ultralow loss cannot be achieved due to the existence of the weak absorption tail. However, it is expected that the chalcogenide glass fibers can be used in short fiber-length applications such as in the remote monitoring and delivery of CO laser radiation. This is due to their wide operating wavelength ranges of0.9-6\mum for As-S,1.3-9\mum for As-Ge-Se, and0.8-5\mum for Ge-S, in which losses can be reduced to below 1 dB/m.