Axial strain and temperature sensor based on tapered biased four-core fiber operating at dispersion turning point

An axial strain and temperature sensor based on tapered biased four-core fiber (BFCF) operating at the dispersion turning point (DTP) is proposed. The non-adiabatic tapered BFCF (Non-AT BFCF) and adiabatic tapered BFCF (AT BFCF) operating at the DTP were fabricated using the two-step tapering method and the one-step tapering method, respectively, and their axial strain and temperature characteristics were simulated and experimentally investigated. The experimental results show that the maximum sensing sensitivities of Non-AT BFCF are 365.6 pm/mu epsilon and 2904 pm/degrees C in the ranges of 0-200 mu epsilon and 30-70 degrees C, respectively. The maximum sensing sensitivities of AT-BFCF are 261.14 pm/mu epsilon and 2280 pm/degrees C in the ranges of 0-300 mu epsilon and 30-70 degrees C, respectively. The sensor is highly sensitive to axial strain and temperature. It has a promising future in measuring physical quantities such as weak strain and temperature.