A weakly-coupled taper-based seven core fiber (TSCF) structure sensor for refractive index (RI) and temperature measurement with a fiber ring cavity laser in 2 μm band was proposed and demonstrated. The TSCF fiber structure acts as both the sensing head and the filter of the laser. Compared with the conventional broadband sensing system, the laser sensing system we proposed has a higher optical signal to noise ratio (OSNR) of ~40 dB and a narrower 3 dB bandwidth of ~0.05 nm. By exposing the TSCF segment to the increasing RI solutions, the output wavelength will have a redshift. A sensitivity of 549.599 nm/RIU was obtained with the RI of NaCl solution changing from 1.3325 to 1.3793. While for temperature measurement, a sensitivity of −4 pm/°C was achieved with the temperature ranging from 35 °C to 70 °C. Notably, the sensing system we proposed shows the merits of marrow 3 dB bandwidth, easy construction, high resolution, high signal-to-noise ratio, and easier to monitor.

提出并论证了一种基于锥度的弱耦合的七芯光纤（TSCF）结构传感器，该传感器用于通过2μm波段的光纤环形腔激光器测量折射率（RI）和温度。TSCF光纤结构既充当激光的传感头，又充当滤波器。与传统的宽带传感系统相比，我们提出的激光传感系统具有较高的光信噪比（OSNR），约为40 dB，较窄的3 dB带宽，约为0.05 nm。通过将TSCF段暴露在不断增加的RI解决方案中，输出波长将发生红移。当NaCl溶液的RI从1.3325更改为1.3793时，灵敏度为549.599 nm / RIU。在进行温度测量时，温度范围为35°C至70°C，灵敏度为-4 pm /°C。值得注意的是