Study On Nanoliter Liquid Volume Fiber Refractive Index Sensor Based On Mode Interference

In recent years,with the continuous in-depth research on optical fiber,optical fiber sensing technology has been rapid development,has important practical value and broad application prospects.Among various types of optical fiber sensors,refractive index sensors have received extensive attention due to their great potential in emerging biochemical and medical applications.V-groove optical fiber(VGF)is coreless optical fiber with an open V groove.It is an excellent refractive index sensor due to the V-groove can be convenient to interact with the environment.In this dissertation,the sensing characteristics of VGF are analyzed and explored.The main work is as follows:First,the basic theory of the Single Mode-V-groove-Single Mode(SVS)multimode interferometric optical fiber sensing structure based on the V-groove fiber is explained.At the same time,geometric modeling and simulation of the sensor structure are performed based on the finite element method,and the VGF mode distribution and the Light intensity distribution and simulation analysis of broadband transmission spectrum.Master the manufacturing process of SVS sensor and make several samples.Secondly,the theoretical simulation analysis and experimental study on the refractive index sensing characteristics of SVS fiber sensor based on V-groove fiber core are carried out.The sensor is filled with a liquid with a low refractive index lower than the fiber itself and a liquid with a high refractive index higher than the fiber itself.The end mode distribution of excitation in VGF is simulated,and the influence of different length of VGF and liquid radius on transmission spectrum is obtained.The SVS refractive index sensor based on V-groove fiber core is optimized and fabricated.The experimental results show that the sensitivity of SVS sensor is 159.696 nm/RIU when the external refractive index is in the range of 1.33?1.37 and 960.11nm/RIU when the external refractive index is in the range of 1.66?1.70.Finally,the theoretical simulation analysis and experimental study of SVS fiber optic sensor refractive index sensing characteristics based on liquid core are carried out.The sensor is filled with a liquid with a low refractive index lower than the fiber itself and a liquid with a high refractive index higher than the fiber itself.The end mode distribution of excitation in VGF is simulated,and the influence of different length of VGF,liquid radius and external temperature on transmission spectrum is obtained.The SVS refractive index sensor based on liquid core was optimized and fabricated.The experimental results show that the sensitivity of the SVS sensor is 870.43nm/RIU when the external refractive index ranges from 1.63 to 1.68.The SVS sensor designed and manufactured in this dissertation has the advantages of simple structure,required sample volume at n L level,rapid and effective detection,etc.,and has a wide range of application scenarios in the field of biomedical detection.