Design and analysis of a new type of pressure sensor based on the high-birefringent photonic crystal fiber

Abstract

In this paper, a new type of fiber optic press sensor based on polarization modulation is proposed and analyzed. The sensor is equipped with a high-birefringent photonic crystal fiber (HB-PCF) as sensing unit and used to measure the pressure in gaseous and liquid media. The linear polarized light injects into HB-PCF with 45° angle at the slow axis and the output light is separated into two perpendicular polarized light with 0° and 90°. Then one of them is rotated 90°, which combine with the other to form light interferometer. Pressure load affects the birefringence of HB-PCF, leading to the variety of output light intensity. The analysis result shows that the centripetal pressure increases the effective refractive index of polarization model in both fast and slow axes with a linear relationship of 8.97×10-6 RIU/MPa and 6.48×10-6 RIU/MPa respectively, so that tends to counteract the birefringence of the HB-PCF caused by its asymmetric structure, with a linear relationship of 2.49×10-6 RIU/MPa. Consequently, the pressure vary from 0 to 100 MPa can be inferred by the output light visibility. The proposed sensor has many advantages such as small volume, simple structure, strong environmental, and tolerance, etc. It can be widely used in pressure measurement and structure health monitoring.