Highly Sensitive Fiber Sensor Of Refractive Index And Temperature Based On Surface Plasmon Resonance In Side-Polished Technology

In recent years,Surface plasmon resonance(SPR)sensors attract great research interests,SPR sensors are widely employed in biotechnology,medical diagnosis,drug screening,food safety and other fields owing to its unique advantages such as simple operation,high sensitivity,and label-free.A fiber-based SPR sensor shows great superiority compared with other substrates,such as its high stability,small size,system compatibility,strong resistance to electromagnetic interference,high-degree integration.In this work,the fabrication of fiber SPR sensor based on single-mode fiber is demonstrated.A side-polished single-mode fiber is prepared by wheeled polishing.Then,the gold film is coated on the surface of the side-polished fiber by magnetron sputtering.For evaluating the performance of the sensor,we used it to detect the RI of samples of index matching oil.The sensor shows a non-linear response to the refractive index(RI).The sensitivity increases with increasing refractive index.The sensors exhibite a sensitivity of ~1651 nm/RIU at the value of 1.300 to 1.370,and it increases exponentially as the refractive index is greater than 1.400,(at which the sensitivity is ~4642 nm/RIU).The sensitivity of the sensor reaches 12093 nm / RIU as the RI is to 1.430.Great research efforts are made for improving the sensitivity of the SPR sensor in aqueous solution owing to the importance of the sensitivity in aqueous solution for biochemical detection.With numerical simulation,we found that a polymer fiber based SPR sensor(in which the core index is 1.357,compared with the core index of ~1.45 for silica fiber)can realize a sensitivity up to 36600nm/RIU for the 1.355 RI sample,which is 1 order higher than silica fiber-based one.The the simulation results are varified with experiments.We also use our single mode-based SPR sensor to realize a highly sensitive temperature sensor,by coating an additional polymer layer(of which the refractive index is ~1.400)on the metal layer of the side-polished fiber SPR sensor.In the 25-100? region,the sensor resonant wavelength of the sensor and the change of temperature show a good linear correlation with a correlation coefficient of 0.9983 and a temperature sensitivity of-0.978 nm/?.