The Research Of Optical Fiber Surface Plasmon Resonance Temperature Sensor

Surface plasmon resonance(SPR)is a near-field optical phenomenon which exists at the interface of two mediums with opposite dielectric constants.It is a surface-bound electromagnetic wave,which caused of the incident light interacts with the electrons at the interface between a metal and a dielectric.Surface plasmon resonance sensing technology has some advantages of high sensitivity,free marking of samples,real-time monitoring and good repeatability.Fiber optic sensor technology has been one of the most potential sensor technologies,due to its small size,light weight,strong repeatability,resistance to external interference and corrosion,optical fiber sensors are widely used in industrial production,medical treatment,aerospace and other fields.Miniaturization and integration trend of sensor development is important.Combining with optical fiber sensors and SPR sensing technology,optical fiber SPR sensors can achieve high sensitivity sensing,miniaturization and integration,which show a good application prospect and huge development potential,and are research hotspot of sensor technology.Temperature is an important factor in laboratory testing and industrial manufacturing monitoring.Optical fiber surface plasmon resonance sensors also have potential for research and application in temperature measurement.In this paper,we research the optical fiber SPR temperature sensors in experimentally and theoretically.Combining with the characteristics of fiber SPR temperature sensor structure,processing technology and excellent performance of temperature sensitive materials,we establish a theoretical sensing model to optimizing the parameters of sensor and sensing characteristics;we design several optical fiber SPR temperatur sensors which is efficient and practical and build sensor testing system;we conduct a series of experiments and data analysis to improve the feasibility of our optical fiber SPR temperature sensing systems.Major research works are as follows:1.This paper expounds the basic properties and theories of SPR,characteristics and research progress of SPR sensing technology.Based on the basic theory of surface plasmon resonance and optical fiber sensing technology,we analysis the optical fiber SPR sensing technology,study and expound the optical fiber SPR sensing system,established the optical fiber SPR sensing system model.Finally,we analysis and optimize the influence of various parameters in the theoretical model on the sensing characteristics.2.In this paper,we propose and demonstrate a dual-channel self-calibration multi-mode optical-fiber(MMF)surface plasmon resonance(SPR)thermometer.The structure of this thermometer is mainly composed by dual sensing channels,in which one channel is coated with a gold layer surrounded by liquid crystal(LC),and the other is prepared with bilayers of silver and thin indium tin oxides(ITO)layer.The gold channel is the main channel,and the channel of ITO layer with high refractive index is viewed as a configuration of self-calibration.The experimental results of the system show that the temperature sensitivities are 1.006 nm/°C in the range of 20 to 34 °C and 0.058 nm/°C in the range of 35 to 80 °C.Particularly,at the phase transition temperature 34.5 °C of changing from nematic to isotropic phase of the LC,the temperature sensitivity shows a step increase of 6.8 nm with a unit temperature change.This structure can be highly advantageous for temperature controlling and alarming in laboratory monitoring and industrial production.3.We research the influence of fiber grinding angle on the sensing characteristics of optical fiber SPR sensor and make a reflecting optical fiber SPR temperature sensor based on fiber grinding technology.In order to successfully stimulate the SPR phenomenon and complete the reflecting sensing,we design the optical fiber sensing probe which ending is ground into an asymmetric wedge with the angle of 90°.Combining with the temperature feature of polydimethylsiloxane(PDMS),we built a sensing model to optimize the grinding angle.We choose the grinding angle is 83° and design 50 nm thinkness of gold film to sensing part and 300 nm thinkness of gold film to reflecting part.Finally,the sensor was tested and found to have-2.02nm/°C temperature sensitivity in the temperature range of 20-90 °C.This optical fiber SPR temperature sensor has a good performance in temperature measurement,and the more important is simpler in the measurement method,more suitable for industrial production of the temperature test application.It is a good commercial fiber SPR temperature sensor prototype.As a conclusion,we summarize the paper and put forward prospect to the research work of SPR sensors.Describing the influence of nano-pattern structure and nano processing technology on SPR temperature sensors.The sensitivity and integration level of SPR sensor system are expected to be further improved.