A distributed optical fiber pressure sensor based on Brillouin scattering technique is proposed and experimentally demonstrated, where double-layer polymer coatings are used on the single-mode fibers (SMF) to improve the Brillouin frequency shift (BFS) pressure sensitivity. The single-coated and double-coated fibers are designed to demonstrate their BFS pressure sensitivity, where the outer coating radius of double-coated fibers are 450 μm, 1000 μm and 1500 μm, respectively. Experimental results show that the BFS pressure sensitivity are -0.74 MHz/MPa, -1.61 MHz/MPa, -2.59 MHz/MPa and -3.51 MHz/MPa in the pressure range of 0-30 MPa for above four kinds of fibers. According to the experimental results, it can be concluded that the BFS pressure sensitivity can be improved with increasing of outer coating radius or decreasing of outer coating Young's modulus and Poisson's ratio. The maximum BFS pressure sensitivity is measured about 5 times higher than single-coated SMF, it is of great significance for SMF to be used in practical distributed pressure measurement.
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