Technology Of Optical Fiber Grating Pressure Sensing

The fiber Bragg grating(FBG) become one of optical passive devices with the fastest developing speed in recent years. It has many advantages such as anti-electromagnetic, anti-eorrosion, highsensitivity, small size, light weight and so on, beeause of those advantages, it has been used in sensor fields. It can check strain, temperature, pressure,ect. And it becomes a focus in optical fiber sensing fields.In this paper, firstly, the recent developments in the technologies of sensing fiber gratings, the characteristic of FBG sensors and the FBG pressure sensing technology development in the world are reviewed. On the basic of the FBG’s coupling model theory, analyzed the propagation of light in FBG and derived equation of FBG. Various fabrication method’s theory of fiber gratings are described systematically. The temperature, strain and Pressure sensing principles of fiber grating were analyzed.Secondly, there are two key issues for fiber grating sensors, the cross sensitivity with temperature and the sensitivity of sensor. Cross sensitivity problem is studied. Discuss kinds of solutions of simultaneously measuring strain and temperature with fiber grating sensors in details. The advantages and disadvantages of each method are analyzed and compared. And we proposed that the use of passive temperature compensation as well as real-time temperature of residual effect of the initiative amendment to the temperature sensitivity. On the basis of the mechanical theory of elastieity, through theoretical derivations, the prineiple of optical fiber grating pressure sensor which is based on the fixed circular plate diaphragm was got. On the basic of theoretical analysis, optical fiber grating was combined with the fixed cireular plate diaphragm, by measuring the offset of optical fiber grating center wavelength, pressure signal was got.Finally, through testing the charaeteristics of optical fiber grating temperature and strain, it proved that the use of temperature compensation can achieved on the pressure, temperature measurements at the same time. The result showed that the sensor had good resolution, linearity, and precision. It is also showed that this structure FBG pressure sensor can meet the measurements of different range and sensitivity by changing the diaphragm’s parameters, such as geometry size.