Research On High Sensitive Fiber Pressure Sensor Based On Off-Center Diaphragm Reflection

Optical fiber sensor is an sensing technology of measuring the outside signal, which using the light wave and optical fiber as carrier and medium, respectively. And it has some advantages of anti-electromagnetic interference, corrosion resistance and so on. It is suitable for measuring in long distance, flammable and explosive environments. High sensitive fiber pressure sensor based on off-center diaphragm-reflection is one type of optical fiber sensor, it uses optical fiber receiving the reflection of diaphragm, and probes the pressure according to the reflected light intensity or phase change; It not only has simple structure, reliable performance and the advantages of flexible design, but also can measure the displacement, velocity, flow rate, voltage and many other physical quantities parameters.In this paper, the design thought of the proposed fiber pressure sensor based on off-center diaphragm-reflection is listed as follows:fiber collimator is used to replace the optical fiber, and the collimator at the off-center position of diaphragm, the beam reflection angle can be changed when pressure is applied on diaphragm, thus light intensity of returned to collimator can be changed. The detection mechanism is based on incident-angle sensitive rather than traditional working-distance sensitive. Compared to the single-mode fiber and multi-mode fiber, collimator has higher parallel light beam, smaller beam divergence (<0.25°), longer working distance (～10cm) and higher sensitivity coupling efficiency. Therefore, the sensor has the characteristics of high sensitivity and easy fabrication.The sensor is fabricated on the basis of theoretical analysis, the measuring results are listed as follows:A sensitivity of1.11dB/KPa and0.16dB/KPa can be achieved with silicon diaphragm thickness of100μm and150μm, respectively. The measuring range can be tuned by changing the pressure in the sealed diaphragm cavity (i.e., a detection range from0.001MPa to0.048MPa can be shifted to another range from0.032MPa to0.09MPa), and higher sensitivity can be obtained by decreasing the thickness of diaphragm.The main content of the paper as follows, firstly, introducing the characteristics, classification and development of the fiber sensor. Secondly, explaining the typical structure and current situation of the research about optical fiber pressure sensor. Thirdly, detailed expounding the design and fabrication of the reflective intensity-modulated fiber pressure sensor of the paper. Finally, introducing the measure plan and theoretical analysis of the fabricated optical fiber sensor, and the full text is summarized, and on the base of the work what has done in this paper, the future research work is prospected.