| Based on understanding the advantages and disadvantages of three types of Fabry-Perot cavity, the intrinsic Fabry-Perot cavity, the extrinsic Fabry-Perot cavity and the in-line Fabry-Perot cavity, two Fabry-Perot cavities based on eccentric ring reflector are proposed. One is the intrinsic Fabry-Perot temperature sensor with high sensitive to temperature and high visibility interference spectrum; another is extrinsic Fabry-Perot refractive index sensor with structural stability and low sensitive to temperature. It is analyzed and simulated the principles of optics of these eccentric ring reflector Fabry-Perot cavity. These two sensors are fabricated according to the theory, and get their respective properties of these two sensors. These two Fabry-Perot cavities enrich optical fiber Fabry-Perot interferometer sensors family, to further expand its application areas. Main contents are as follows:1. It is analyzed and simulated principles of optics of these two eccentric ring reflector Fabry-Perot cavity. The ratio of reflected light and transmission light is decided by different axis offset when the multi-mode photonic crystal fiber (MM-HNA-5) spliced to the Corning single mode fiber (SMF28e). So the optical Fabry-Perot can achieve an high visibility; Two sections different diameter size hollow fibers serially are spliced to Corning single mode fiber (SMF28e), an high visibility can achieved by axis offset of the second reflector and SMF28e. And different splicing power in splicing two reflector of Fabry-Perot, another the Fabry-Perot cavity is an open-cavity.2. The fabrication of the corning single mode fiber (SMF28e) splicing to the multi-mode photonic crystal fiber (MM-HNA-5). Based on prior to fabricating hollow-core photonic crystal fiber Fabry-Perot in the laboratory, determines fusion parameters of temperature Fabry-Perot sensor. Discovery the sensor's advantage is that the high thermo-optical coefficient of fiber material causes the high sensitive to temperature of the Pabry-Perot sensor. High temperature anneals, high temperatures measurement, high temperature stability and low temperature measurement are study in experiments. Finally the temperature sensor measurement range (experimental value of -20 ~ 1200℃, theoretical value of -200~1200℃) and optical path difference normalized temperature sensitivity are achieved. The value of optical path difference normalized temperature sensitivity is similar to the theoretical value, about 290nm/(℃?cm). The normalized optical path difference sensitivity of the low temperature section is 271.162nm/(℃?cm), it is slightly smaller than the normalized optical path difference sensitivity high temperature section. And it has good linearity and repeatability.3. The fabrication of two sections different diameter size hollow fibers serially spliced to the corning single mode fiber (SMF28e). The first reflector is fused using higher energy (the energy level of fusing machine is 100 grade), the second reflective surface was fused energy slightly lower (the energy level of fusing machine is 80 grade), and a small diameter hollow optical fiber is spiced to a bigger diameter hollow core fiber with offset. So the two reflective light can be similar, the visibility of the Fabry-Perot is the highest. And the Fabry-Perot cavity is open cavity. The measurement principle is study, and these refractive index measurements rang using wavelength shift demodulation (the refractive index different of maximum and minimum refractive index is about difference between the refractive index). At last 10-6 a refractive index of each wavelength drift ~1.467pm and ~5.307×10-6 refractive index resolution are achieved in refractive index measurement experiment. And because the material of fiber has a small thermal expansion coefficient, the refractive index sensors will a small cross-impact to the measurement of refractive index. |
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