Three-core fiber cascade asymmetric dual-taper robust structure for the simultaneous measurement of a mass concentration of a glucose solution and temperature

This study aimed to achieve the simultaneous measurement of a mass concentration of a glucose solution and temperature. We proposed an asymmetric dual-taper sensor approach, based on a cascade structure of three-core fiber, which can effectively overcome cross-sensitivity. With this approach, our experiment successfully fabricated a sensor with a distance of 3 mm between the double tapers: One taper was fabricated at the three-core fiber (TCF) near the TCF-multimode fiber junction and the other taper was fabricated at the TCF–MMF junction. Afterwards, the length of the sensor increased by only 1.31 mm, which indicated that the sensor was not easy to break. The interference contrasts of the two interference resonance dips exceeded 16 dB. Considering the feasibility of double-parameter sensing and the improvement of sensitivity, an asymmetric double-taper was designed. The temperature responses to the proposed sensor were tested in the range from 25 °C to 75 °C, and responses of the mass concentration of glucose solution were tested in the range from 1% to 15%. Experimental results showed that the two interference peaks of an asymmetric dual-taper robust structure had different sensitivities to changes in the mass concentration of the glucose solution and to temperature. Moreover, these two parameters can be simultaneously demodulated by use of matrix method. © 2020 Elsevier B.V.