A tapered plastic optical fiber (POF) assisted by a long period grating (LPG) is proposed as a refractive index (RI) sensor. A tapered POF assisted by a corrugated surface LPG is fabricated by the heating and drawing method and simple mechanical die press print method. By changing the structural parameters of the tapered POFs with LPG, the RI sensing performance of the obtained sensor are evaluated. It shows that the structure parameters of sensor affect the RI sensing performance, and the sensor with a smaller diameter of the tapered POF and a deeper groove depth of the LPG exhibits better RI sensing performance. When the POF with a diameter of 1mm is heated and drawn to form a tapered POF with a diameter of 600μm, then an LPG with a period of 300µm, groove depth of 150µm is fabricated on it, the RI sensitivity of 590.7%/RIU is obtained in the measured RI range
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