Strain-Insensitive Temperature Sensor Based on Few-Mode Fiber and Photonic Crystal Fiber

Based on few-mode fiber (FMF) and photonic crystal fiber (PCF), a new temperature sensor with a FMF-PCF-FMF hybrid construction has been developed. Furthermore, the sensor has a longitudinally symmetrical structure that makes it have a flexible sensor head, which enhances the practical performance. Simulated results show that there are three resonant peaks with extinction ratio above 18 dB in the wavelength from 1630 nm to 1720 nm, and the temperature can be measured by calculating wavelength shift of resonant peaks. The experimental results show that the temperature sensitivity of the proposed sensor is as high as 38.6 pm/°C when the temperature ranges from 20°C to 80°C. Meanwhile, the strain sensitivity of the proposed sensor is as low as −0.457 pm/μϵ when strain ranges from 0 to 3000 μϵ. The high temperature sensitivity and ultralow strain sensitivity indicate that the proposed sensor can effectively eliminate the cross-sensitive issue of temperature and strain. In addition to excellent sensing performances, simple and compact structure make the proposed sensor be potential in practical applications.