Mid-IR fiber-optic sensors based on especially pure Ge₂₀Se₈₀ and Ga₁₀Ge₁₅Te₇₃I₂ glasses

Optical fibers on the base of especially pure Ge20Se80 and Ga10Ge15Te73I2 glasses are prepared and applied as the material of sensing elements. To connect the sensing element to the attachment of an IR Fourier spectrometer, flexible fibers based on polycrystalline silver halides and As-Se glasses are used. The prepared multimode As38Se62/As35Se65 fiber has a minimum optical loss of 40 dB/km at 3 mu m that is a record low value among coreclad selenide fibers. Fiber-optic probes with various combinations of the material of flexible fibers and sensing elements are manufactured and tested for FEWS analysis of different model organic mixtures. The promising version of a fiber-optic probe is shown to be a device with polycrystalline silver halide flexible fibers and the chalcogenide fiber sensing element. The Ga10Ge15Te73I2 fiber tips allow analysis in the 5-15 mu m spectral range. The U-shaped Ge20Se80 sensing elements with a taper show the highest sensitivity.