Study On Fiber Bragg Grating Pressure Sensor

Fiber Bragg Grating has many unique advantages, such as small size, light weight, strong corrosion resistance, and strong anti-interference of electromagnetism capability etc, so it has become one of the most promising passive optical components. However, the bare FBG has low pressure sensitivity and is simultaneous sensitive to temperature/strain; it needs to take effective method to solve these questions in practical application. Therefore, this paper has studied on the structure design of FBG sensor probe, the problem of temperature/strain cross-sensitivity, as well as increasing pressure sensitivity and packaging technique issues etc.FBG is fabricated using the method of phase mask, based on the full analysis of the temperature/strain characteristics for bare fiber grating, different materials of the same four sensitive probes (highly flexible stainless steel 1Cr₁₈Ni₉, low carbon steel Q_235B, copper and aluminum) are designed. The research adopts the finite element analysis method to make the simulation analysis for the stress and deformation under uniform pressure distribution. To solve the problem of temperature/strain cross-sensitivity, design the structure of pressure sensor to realize temperature compensation, grating pressure/temperature and referring grating temperature are calibrated respectively through experiment, achieved the distinction between temperature and strain measurements. To increase pressure sensitivity, sensitive probe material selection, material thickness, FBG paste location, adhesives selection and annealing characteristics are studied respectively. The results show that FBG pressure sensor has good sensitivity, linearity and repeatability, it has been found that the pressure sensitivity of experimental measurements value consistent well with theoretical value. In packaging technology, this paper attempts to use the metal packaging technology of pressure sensor, testes the characteristics of the metal packaging grating pressure\temperature, and compares with adhesive packaging FBG pressure sensor, the results prove that the metal packaging FBG pressure sensor has the advantage of high precision, good mechanical strength, strong stability and reliability, it's suitable for high temperature under pressure measurement.FBG pressure sensor distinguishes well pressure\temperature, improves pressure sensitivity, has the advantage of simple structure, good linearity and respectively.