Research On The Microstructured Optical Fibre-based Gas And Surface Plasmon Resonance Sensors

Microstructured Optical Fibres(MOFs) also known as photonic crystal fibres(PCFs) when the fibre holes are periodically arranged, are composed of an array of air holes running along their entire length and present a diversity of new features beyond what conventional optical fibers can offer. Due to their unique geometric structure, the MOFs present special properties and capabilities that lead to an outstanding potential for sensing applications. In this paper, the gas sensors by using MOFs were investigated both theoretically and experimentally. And the surface plasmon resonance sensors by using MOFs were designed and analyzed for refractive index and temperature sensing application. The main contents of this dissertation are as follows: 1. Gas sensorsA suspended-core fiber(SCF) with subwavelength core diameter has been numerically analyzed for gas sensing application. The dependence of the relative sensitivity, effective mode area, and confinement loss on the fiber parameters as well as the refractive index of fiber material is investigated. The proposed SCF with subwavelength core diameter is very promising for developing a high-sensitivity gas sensor with large-effective mode area and low-confinement loss.A three-point detecting acetylene gas sensor was designed by using Photonic bandgap MOFs and dense wavelength division multiplexing(DWDM) filters. Three absorption peaks of acetylene gas: 1530.371 nm, 1532.830 nm and 1536.712 nm were chosen to detect the absorption spectrum of the gas in the three gas cells. 2. Refractive index sensorsA surface plasmon resonance(SPR) sensor based on a six-hole MOF was proposed. The six large holes should facilitate the fabrication of the coated sensor structure and the infiltration of the analyte. The relationship between the sensitivity of SPR sensor and the refractive index of MOF materials is demonstrated.A SPR sensor based on exposed-core MOFs(EC-MOFs) is presented and numerically characterised. The SPR sensing performance for a large refractive index range from 1.33 to 1.42 is evaluated.To solve the phase matching and analyte filling problems in the MOF-based SPR sensors, we present the D-shaped hollow core MOF-based SPR sensor. We numerically investigate the effect of the air hole in the core on the SPR sensing performance, and identify the sensor sensitivity on wavelength, amplitude and phase. 3. Temperature sensorsA temperature sensor based on SPR supported by a six-hole MOF was demonstrated. The air holes of the MOF are coated with a silver layer or filled with a silver wire. A liquid mixture(ethanol and chloroform) with a large thermo-optic coefficient is filled into the PCF holes as sensing medium. And high temperature sensitivity can be achieved.