A Compact Four-Wave Mixing-Based Temperature Fiber Sensor With Partially Filled Photonic Crystal Fiber

In this paper, a compact temperature sensor was constructed based on controllable four-wave mixing (FWM) achieved by a partially filled solid-core photonic crystal fiber (PCF). With the help of a hollow-core fiber, the air holes of the PCF were partially filled with one layer, two layers, and four holes, respectively, thereby realizing a controllable output of signal wave. The response to temperature was tested and analyzed in the experiment. A sensitivity of 0.61 nm/°C was obtained from the room temperature to 150 °C with a fiber shortened to 25.8 mm. Both experimental and theoretical results showed that the response to the temperature could be with great linearity for the one-layer filled PCF, and the sensitivity of FWM-based sensor was almost unchanged when the sensing fiber is shortened, which could be benefit for constructing compact or ultra-compact inline FWM-based sensors. Furthermore, the FWM-based temperature sensor also presented good stability against the fluctuation of the excited power.