Strain-insensitive temperature sensor based on a few-mode dual-concentric-core fiber

We report on a compact strain-insensitive fiber temperature sensor based on a few-mode dual-concentric-core fiber (FM-DCCF). The proposed sensor simply involves a section of FM-DCCF spliced to lead-in and lead-out single-mode fibers (SMFs). The FM-DCCF with unique refractive index distribution supports a few number of guided modes. The high-order mode in the FM-DCCF is coupled from the fundamental mode in the lead-in SMF, and then the interference spectrum of them can be obtained in the lead-out SMF. By monitoring the variation of the wavelength, the sensor can be applied in temperature measurement with a sensitivity as high as 52.79 pm/°C. In addition, the wavelength drift of the sensor is almost immune to the cross impact of axial strain with the sensitivity of 0.23 pm/με.