Research On Novel Optical Fiber Sensors Based On Fluorescent Nanomaterials

The Internet of Things(IoT)category has grown exponentially in the past decade and has significantly reshaped human life in all aspects.The optical fiber sensor with both communication and sensing functions will gradually become a bridge connecting people and the whole world.At present,a variety of optical fiber sensors can provide ideal and high-performance methods for detecting various physical quantities.It is worth noting that optical sensors based on new material sensitive coatings are one of the development trends of optical fiber sensing technology.From the perspective of combining the science of fluorescent nanomaterials with optical fiber technology,this thesis deeply studies the design and application of optical fiber devices based on fluorescent nanomaterials.Specifically,it develops a micro-fiber gas sensors based on quantum dot of visible fluorescence and a up-conversion nano-particle fluorescence enhanced micro-fiber sensor for relative humidity sensing.And it also has proposed the structure design of multi-parameter optical fiber sensor based on multi-granularity quantum dot fluorescent nano-materials.This thesis first briefly introduces the research background and significance of new optical fiber devices based on fluorescent nanomaterials,and summarizes the research status of fluorescent nanomaterials science and optical fiber sensing technology respectively,and lists the main research contents and main innovations of this thesis.Then it discusses how to effectively apply fluorescent nanomaterials to optical fiber sensing technology from three aspects,including the optical fiber structure and system architecture that the fluorescent nanomaterials can be adapted to,the principle and mechanism of optical fiber devices based on fluorescent nanomaterials,and the fabrication process of the nano-material fluorescence-based optical fiber devicesThis thesis has developed a micro-nano fiber sensor based on quantum dot of visible fluorescence,which is a kind of the fluorescent nanomaterials.It has the characteristics of small size,light weight,simple structure,batch reproducible fabrication process,fast response,resistance to vibration and bending interference,etc.,and can achieve ultra-low concentration detection of ethanol vapor.The thesis expounds the structure principle and preparation process of the sensor,and verifies the anti-bending,sensitivity,temperature response and time response characteristicses of the sensor through specific experiments.In addition,this thesis has also independently developed a precise and controllable optical fiber electric coating system,which realizes the repeated batch preparation of material-coated optical fiber sensors.This thesis also developed a micro-nano fiber optic RH sensor based on up-conversion nano-particle fluorescence enhancement.The self-synthesized cellulose liquid crystal film is used to enhance the fluorescence of the up-converting particles,which greatly improves the signal-to-noise ratio of the sensing signal and the sensitivity of the sensor,and can inhibit temperature cross-sensitivity.Specific experiments have verified the improvement of the signal-to-noise ratio of the optical signal,the sensitivity and temperature response characteristics of the sensor.This work provides a new idea for the application of the natural porous periodic structure,like cellulose liquid crystal membrane,in the field of optical fiber sensing technology,and greatly reduces the cost of preparing high-performance sensors.At the end of the thesis,the thesis proposed the design of a multi-parameter optical fiber sensor based on multi-granularity quantum dot fluorescent nano-materials.The structure includes a photonic crystal fiber doped with multiple quantum dots and a composite fiber grating.The feasible fabrication scheme of the sensor is described.The photonic crystal fiber and the composite fiber grating were simulated respectively,and the main parameters were analyzed and optimized.The principle of multi-parameter sensing is described,and a more compact structure optimization concept is further proposed,which provides a new idea for the application of more kinds of fluorescent nanomaterials to multi-parameter optical fiber sensing.