Ultralow loss single-mode fiber design for 25–6-μm band operation

This paper describes the design for single-mode fibers whose operation wavelengths leading to ultralow loss <0.01 dB/km are in the 2.5–6-μm range. We evaluate the excess loss caused by uniform bending, microbending, and splicing with the formula used for silica-glass fiber. The possibility of preparing the ultralow loss fiber is discussed.