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The optical fiber temperature sensor based on the coupling mechanism of the miniature pull-tapered dual-core photonic crystal fiber has been designed. The dual-core photonic crystal fiber coupling structure was realized by tapering the two cores of the dual-core photonic crystal fiber transversely. At the same time, the end surface of the fusion taper of the dual-core photonic crystal fiber was plated with a total reflection film, thereby a reflective dual-core micro-fiber pulltaper coupler developed. According to the above-mentioned reflective fiber coupler light guide transmission mode, combined with optical waveguide theory, the coupling mechanism of the dual-core photonic crystal fiber was studied, and the relationship between the structure of the dual-core photonic crystal fiber coupler and its light guide characteristics is studied. The increase of the effective refractive index and the coupling length will cause the centerwavelength of the fiber coupler to shift to the long wavelength direction, and the increase of the coupling diameter will cause the center wavelength of the fiber coupler to shift to the short wavelength direction. Based on the above mechanism, an optical fiber temperature sensor based on a miniaturized dual-core photonic crystal fiber coupling structure was developed, and the temperature response characteristics of the sensor were studied and analyzed through experiments. The experimental results show that the measurement temperature range of the miniaturized dual-core photonic crystal fiber temperature sensor can be from 96°C to 1425°C ,and the temperature sensitivity is 0.024nm/°C. The miniaturized dual-core photonic crystal fiber temperature sensor has the advantages of miniaturization, large range, high sensitivity, and immunity to electromagnetic interference.
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