We demonstrated a compact fiber sensor for the Refractive Index (RI) and temperature measurement based on a balloon-shaped Mach-Zehnder interferometer (MZI) with no need of special fibers or coating sensitizer material. To enhance the sensitivity and structural stability of the sensor, a spherical structure is added on both sides of the balloon-shaped single mode fiber (SMF). The fiber length between the two spherical structures is L, three kinds of spherical MZI with L of 3 cm, 3.5 cm and 4 cm were prepared, and their sensing performance was studied. The experimental results show that the RI and temperature sensitivity of the sensor increase with the increase of L. We get maximum RI sensitivity of 965.1 nm/RIU (refractive index unit) in the RI range of 1.3350–1.3965 and a temperature sensitivity of 178.6 pm/°C in the temperature range of 30–80 °C. Compared with other balloon-shaped sensors, the proposed sensor has higher sensing sensitivity and stronger structural stability, which is conducive to promoting the development of balloon-shaped MZI to satisfy practical demands.

我们展示了一种基于气球状马赫-曾德干涉仪 (MZI) 的用于折射率 (RI) 和温度测量的紧凑型光纤传感器，无需特殊纤维或涂层敏化剂材料。为增强传感器的灵敏度和结构稳定性，在气球状单模光纤（SMF）的两侧增加了球形结构。两种球形结构之间的纤维长度为L，制备了L为3 cm、3.5 cm和4 cm的三种球形MZI，并对其传感性能进行了研究。实验结果表明，传感器的 RI 和温度灵敏度随着 L 的增加而增加。 我们在 1.3350-1.3965 的 RI 范围内得到 965.1 nm/RIU（折射率单位）的最大 RI 灵敏度和 178.6 pm /°C 在 30–80 °C 的温度范围内。