High-Sensitivity Temperature Fiber Sensor Based on Two Cascaded Balloon-shaped Bent SMFs integrated with a Seven-core fiber

A high-sensitivity fiber sensor integrated by two cascaded balloon-shaped bent single-mode fiber (BBSMF) Mach-Zehnder interferometers is proposed and demonstrated. A high-order mode can be greatly stimulated due to embedding a seven-core fiber (SCF) between the two BBSMFs. The experimental results show that the maximum temperature sensitivity of the proposed sensor is -3.35nm/℃ between 13 ℃-71 ℃, which is currently the highest temperature sensitivity, in the BBSMF structure as far as we have ever known. Furthermore, the temperature sensitivity can be optimized by changing the length of the SCF and the diameter of the BBSMF. The proposed sensor has the advantages of easy production, low cost, and high sensitivity, which makes it well-suited for precise temperature measurement applications