White-light interference distributed fiber optic pressure sensor

In order to measure pressure distribution information with a high spatial resolution, a white-light interferometer distributed fiber optic pressure using coupling between two orthogonal polarized modes in polarization-maintaining (PM) fiber is proposed. A low-coherent SLD was adopted as light source of the sensor, and distributed sensing information is obtained by a scanning Michelson interferometer followed the fiber. Mutual coherent intensity can be measured when the optical path difference of two arms in the Michelson-interferometer. compensates the path difference of the two orthogonal polarized modes in PM fiber. The spatial resolution measured by experiment was about 6cm, which coincides with theoretical analysis. Output intensity of sensor is determined by external force, the angle theta(p) between the direction of applied pressure and slow axis of the fiber. The results of experiment on different points of the fiber have shown that output intensity of the sensor is in proportion to pressure with a good linearity.