High-sensitivity sensing in bare Ge-Sb-Se chalcogenide tapered fiber with optimal structure parameters

Abstract In this work, the purified Ge15Sb20Se65 glasses were synthesized through the melt-quenching method and drawn into bare glass fibers with a diameter of 500 μm. The minimum optical loss of this fiber was approximately 1.68 dB/m at 6.0 μm. Then, the fibers were tapered into different waist diameters, containing 244.95, 110.44, and 20.27 μm, for monitoring aqueous ethanol solution. The highest sensitivity was observed when the waist diameter was the smallest of 20.27 μm. On this basis, three tapered fibers with different taper waist lengths were fabricated for aqueous ethanol solution sensing experiment. Experimental results demonstrated that the sensitivity of 15.94 mm taper waist length was more than 3 times as large as that of 11.53 mm, showing that the longer the taper waist length, the better the sensitivity. Finally, based on the fiber evanescent wave theory, the sensing characteristics of the tapered fibers with different waist diameters and waist lengths were numerically simulated.