| Surface plasmon resonance sensors are fit for liquid analyte detection and widely used in the researches of biomolecular interaction analysis and biochemical sensing. Contributing to the ultrasensitive refractive index response,label free,non-destructive and real-time online detection,etc., surface plasmon resonance technology is being applied in various areas,such as health-care,pharmaceuticals,environmental monitoring and food safety. Photonic crystal fibres(PCFs) allow a variety of solid or liquid matrices to be filled into their air holes,and can offer a large overlap between the guided light and the filled matrices. It constitutes versatile platforms for developing compact optofluidic devices. The configuration of SPR develops from the large prism configuration to the SPR based PCF configuration that has advantage in compact structure,real-time measurement and good stability. With a proper design of lattice array,air hole's size,PCF's material and the filled matrix, the functionalized PCF can be obtained. This essay combines the PCF with nanometer level metal ring structure, consists of the following four parts:(1) The theory foundation of the Kretschmann prism mechanism is analyzed in detail, which helps to analyze the excitation condition of the SPP in the 2D cylindrical waveguide. Then the guiding mechanism and the preparation methods of PCF are summarized. With different configurations and position of nanometer level metal rings in PCF,the essay discussed three kinds of PCF-SPR structure,meanwhile proposed the preparation methods of PCF-SPR structure.(2) Based on Yariv's coupled mode theory and super-mode theory of bound mode, this essay discussed the mode coupling mechanism of the leaky mode in PCF-SPR structure: the avoided crossing effect and crossing effect. A simple but representative PCF-SPR structure was adopted with finite element method, the results presented that the mode coupling coefficient occupies an important place in the change of coupling mechanism, which agrees with the theory.(3) A side core PCF-SPR(SCPCF-SPR) liquid refractive index sensor is proposed. Based on the dual core PCF, the mode overlap of SCPCF-SPR is bigger,which contribute to the appearance of the avoided crossing effect and improve the linearity of the SPR based sensor. The maximum sensitivity of 5000nm/RIU among the RI of 1.33–1.44,and the average sensitivity of 9295nm/RIU among the RI range of 1.44 to 1.54 is obtained respectively with the SCPCF-SPR structure.(4) A single-polarization single mode PCF(SPSM-PCF) is proposed. The work first points out the polarization-selective property of the 0th order SPP mode at the gold/liquid interface. Due to band gap-liked effect of the 0th order SPP mode at the gold/liquid interface and large overlap area of the 2nd order SPP mode at the gold/silica interface,the polarization extinction of the proposed SPSM-PCF is all larger than 30dB/cm at the second communication window. Additionally,with a proper RI value of the filled liquid,the avoided crossing effect is appeared and improved the loss difference of the two orthogonal polarized modes. Through changing the outside diameter and thickness of the gold-coated layers,we find that the proposed SPSM-PCF processes a large tolerance of the size deviation of gold-coated layer. This research provides a potential use for the wideband PCF based polarizer with a large loss extinction of the guided and unguided fundamental core mode. |
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