| Surface plasmon resonance sensor is highly sensitive to the changing of the sample refractive index,so it has wide applications in biotechnology and biochemistry sensing field.For the past few years,along with the increasing demand of sensing performance,traditional SPR sensors can only measure single physical quantity,and are easily disturbed by ambient temperature changing,which can not satisfy the existing sensing requirement.Multichannel SPR sensor can measure multiple sample and physical quantity simultaneously with two or more sensing channels to achieve temperature compensation for improving the sensor measurement accuracy effectively.However,the performances of current multichannel SPR sensors,such as sensitivity,full width half maximum and quality factor,still need to improve.In view of the above problems,in this thesis,we carry out a series of researches of novel multichannel SPR sensors based on optical fiber,and provide a number of ways to adjust the resonance wavelength of each different sensing channel to avoid crosstalk.We also analyse and optimize the performance of the SPR sensors in this thesis by a series of theoretical simulations and practical experiments.The main contents of this thesis is as follows:For solving the problem that accuracy of the single channel SPR fiber sensor is easily affected by ambient temperature variation,we fabricate a dual-channel optical fiber SPR sensor based on a v-shaped wedge side-polished eccentric-core fiber.We study the effects of wedge angle and gold film thickness on resonance spectra of the sensor by a series of theoretical simulations and practical experiments to select the best parameters.the sensing characteristics are researched by theoretical simulations and practical experiments.We study the fiber cutting angle,polishing accuracy,fusion parameters and sputtering deposition to fabricate a symmetrical V-shaped fiber groove coated by gold film.We coat a layer of PDMS on one side of the groove to achieve dual-channel RI and temperature sensing for temperature compensation.By high RI of PDMS,we adjust the resonance wavelength of each sensing channel to avoid crosstalk.The experimental results show that the highest RI sensitivity of the sensor is 3376 nm/RIU,and the highest RI detecting accuracy is 5.3×10-5 RIU.In the temperature range of 20-60°C,the temperature sensitivity of the sensor is-2.62nm/°C,and the highest temperature detecting accuracy is 0.06°C.To solve the problem that structure of wedge fiber SPR sensor is relatively weak due to the fusion point,we fabricate a dual-channel optical fiber SPR sensor based on a d-shaped side-polished single mode fiber.We manufacture the extra temperature sensing channel by coating a layer of PDMS on the half of side-polished surface to achieve temperature compensation.We study the modal field distribution of the SPR fiber sensor by FEM,and optimize gold film thickness of each sensing channel.We adjust the resonance wavelength of each sensing channel by coating different thickness of gold film on each channel to avoid crosstalk.The experimental results show that in the RI range of 1.333-1.390 RIU,the highest RI sensitivity of the sensor is 3865 nm/RIU.In the temperature range of 20-60°C,the temperature sensitivity of the sensor is-2.41 nm/°C.Compared with the above-mentioned V-shaped SPR sensor,this D-shaped SPR sensor has higher RI sensitivity,more stable structure and easier assembling.We fabricate a triple-channel optical fiber SPR sensor based on the multi-layer sensing film to solve the problem that SPR fiber sensor is hard to adjust resonance wavelength for multichannel sensing.We adjust the resonance wavelength of each sensing channel by coating an extra layer of titanium dioxide with high RI.We study the resonance wavelength of sensor by FEM,then we draw the conclusion that as thickness of titanium dioxide layer increases,the resonance wavelength red-shifts obviously,and the sensitivity also increases.On such a basis,we coat different thicknesses of titanium dioxide layer of three sensing sub-channels are 10nm,30 nm and 60 nm,the resonance wavelengths of three sensing channels are keep away from each other to avoid crosstalk between each channel.In RI range of 1.333-1.370 RIU,the average sensitivities of the three RI sensing channels are 2568 nm/RIU,3816nm/RIU and 6011 nm/RIU。... |
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