| Recently more and more interests are focused on fiber-optic sensors, for they have several outstanding advantages, including small size, light weight, corrosion resistance, easily multiplexing, immunity to electromagnetic interference, and capability of responding to a wide variety of measurands, etc. The fabrication method, optical characteristics and corresponding applications based on long period fiber grating (LPFG) and photonic crystal fiber Fabry-Perot (F-P) were studied in the past several years, and the research results obtain the initial recognition of domestic and foreign experts. The work is supported by the Key Project of National Natural Science Foundation of China (60537040) and Natural Science Foundation Project of CQ CSTC (CSTC2008BB2165). In this thesis, three novel biochemical sensors are designed and fabricated based on previous studies in laboratory. The characteristics and applications of the above biochemical sensors have been studied by experimental and theory. The main work of the research is given as follows:1. A novel long period fiber grating PH value sensor is designed and fabricated based on LPFG environmental response characteristics. The ordinary long period fiber grating and rotating long period fiber grating is coated with a new PH value sensitive hydrogel. This hydrogel can generate forces when it will meet the PH value standard buffer solution substantially to make its swelling, and will induce the resonant peak wavelength and amplitude change of the LPFG, realizing PH value measurement. The experimental result indicated that: in the PH value range of 4.0~8.0, the resonant peak amplitude of ordinary long period fiber grating PH value sensor is change - 4.77dB, the sensitivity is 1.193dB/PH, the resonant peak wavelength of rotating long period fiber grating is change 2.68nm, the sensitivity is 0.67nm/PH. It is consistent with the theoretical analysis, has the good linearity, and can be used in biomedical PH value measurement.2. A novel optical fiber Fabry-Perot refractive index sensor is designed and fabricated based on the medium refractive index changes when the liquid into the Fabry-Perot cavity, and will induce the optical path difference change of the F-P interference spectrum, realize the refractive index measurement. There are two different lengths of solution refractive index sensors to study, the experimental results show that: the change of optical path difference is large when the refractive index of liquid varies in the corresponding range, the refractive index measurement have the highest sensitivity of 350μm/RIU. This refractive index sensor can also be used to measure the refractive index and concentration of gas. Therefore, it will have great practical value.3. A novel optical fiber Fabry-Perot humidity sensor is designed and fabricated based on optical fiber Fabry-Perot refractive index sensor. The principle is as the following: the F-P cavity is filled with a novel nano-composite hydrogel with a strong water capacity. It is realized that the humidity can be measured by measuring optical path difference of the sensor when the refractive index of hydrogel changes after it absorbed water vapor in the air substantially. The experimental results show that: the optical path difference changes 4.6692μm when the surrounding humidity varies in the range of 38%~98% and the sensitive is 77.82nm/RH (%), the trend is obvious. Therefore, this sensor will have a potential application in our daily life... |
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