Temperature-Insensitive Polarimetric Fiber Strain Sensor with Short Polarization-Maintaining Photonic Crystal Fiber

By incorporating a Sagnac birefringence loop composed of a 3.9- or 5.2-cm-long polarization-maintaining photonic crystal fiber, we demonstrated a temperature-insensitive polarimetric fiber strain sensor with a reduced length of the sensing fiber. The sensing fiber is shortened by more than two times compared with the shortest sensing fiber used in other previous works for localized sensing and sensor compactness. With a 3.9-cm-long sensing fiber, a strain sensitivity of ∼2.34 pm/µε was obtained in a measurement range of 0–10 mε. Temperature sensitivity was measured as ∼21.7 pm/°C, significantly lower than that of the conventional PMF.