Design Of Photonic Crystal Fiber Sensor Based On Surface Plasmon Resonance

A variety of geometric structures and unique optical properties make the photonic crystal fibers show excellent scientific research values and applications prospect in the field of fiber optic sensing,especially photonic crystal fiber sensors based on surface plasmon resonance.The excellent characteristics of high real-time sensing sensitivity and small demand for monitoring samples have gradually made it a research focus in the fields of biochemical detection,gas sensing,temperature monitoring,and food safety.The main contents of the thesis include:?1?In order to realize low-refractive index and high-sensitivity sensing of photonic crystal fibers in the near-infrared band,a photonic crystal fiber refractive index sensor based on surface plasmon resonance was designed.By changing the arrangement of the internal air holes,it achieves the effect of dual-core transmission.A gold nano probe is placed on the part of the outer wall of the optical fiber where is in contact with the circular object channel to be measured.The probe-type structure is beneficial to accelerate the surface plasmon resonance reaction.Numerical simulation of its optical characteristics through the finite element vector software COMSOL,the resonant wavelengths of different refractive indices of the testing object were obtained and the core attenuation spectrum of the core was plotted,the attenuation spectrum of the core is used to analyze the sensing characteristics of the PCF-SPR sensor.The experimental results show that its refractive index measurement range is 1.21¹.25,maximum spectral sensitivity is 11000nm/RIU,the maximum amplitude sensitivity is205.9 RIU^-1,and the refractive index accuracy is 1.8×10^-55 RIU.?2?Aiming at the problem that the optical fiber temperature sensing device generally has a complicated structure and low sensitivity,an elliptical air hole temperature sensing device with high sensitivity is proposed and simulated in this paper.By using surface plasmon technology and optical fiber temperature sensing technology,the temperature sensing is achieved.It is mainly coated with a metal film on the outside of the fiber,a mixture of chloroform and alcohol was used as a temperature-sensitive object,and the simulation was done by the finite element vector software COMSOL.The simulation results show that when the incident wavelength is increased from 0.5?m to 1.0?m,the temperature measurement range is-20¹20°C,the maximum spectral sensitivity is 6 nm/°C,the maximum amplitude sensitivity is1337.12RIU^-1,and the measurement accuracy is 2.85×10^-55 RIU.?3?Combining surface plasmon technology with fiber sensing technology,a high sensitivity D-type photonic crystal fiber based on surface plasmon resonance methane gas volume concentration sensor was proposed and verified by simulation.The metal nano strip are deposited on the outside of the polished surface of the D-type optical fiber and methane-sensitive materials are coated on optical fibers and metal surfaces.The D-type structure promotes sufficient reaction between methane-sensitive materials and methane gas.Numerical simulation of its optical characteristics through the finite element vector software COMSOL,And compares the difference in sensing performance between the traditional metal layer and the metal strip.Simulation results show that when the incident wavelength is increased from 0.9?m to 1.1?m,the measurement range of methane gas volume concentration is 0³%,an average gas spectral sensitivity of 10 nm/%can be obtained.