A Sensitivity Enhancement Method of Optical Fiber SPR Sensor Based on CeF3

To solve the problem of insufficiently high sensitivity of surface plasmon resonance (SPR) sensor, CeF
$_{\mathbf {{3}}}$
material is applied to fiber SPR sensor in this study for the first time, and a CeF
$_{\mathbf {{3}}}$
-assisted SPR refractive index (RI) sensor on the basis of multimode–single-mode–multimode (MSM) fiber structure has been proposed and designed. The theoretical model of sensor with novel structure is presented. Both simulations and experiments are included in this study. The consequences of numerical simulation demonstrate that CeF
$_{\mathbf {{3}}}$
can greatly enhance the sensitivity. It can be seen that the sensitivity of structure in the RI range of 1.33–1.37 can reach up to 8678.83 nm/RIU according to the experimental results. When comparing with the Au film SPR sensor structure, the sensitivity is significantly increased, reaching 4.08 times of traditional Au film SPR sensor. The temperature sensitivity test and repeatability test show that the sensor is not responsive to temperature between 20 °C and 60 °C, which is suitable for use in a wide range of environmental conditions and has good repeatability. CeF
$_{\mathbf {{3}}}$
has the advantages of good biocompatibility and no damage to biological tissues, so the novel sensor that has been proposed has a broad and potential future in biological detection.