Development of high sensitivity pressure sensor using reduced clad FBG

This study focused on the development of high sensitivity pressure sensor based on reduced clad FBG encapsulated in a stainless steel cylinder, partially filled with silicon rubber. The sensor works by means of transferring radial or lateral pressure into an axially stretched- strain along the length of the FBG. The experiment is carried out using two different FBG's have core/clad diameters of 9/125 mu m (FBG1) and 4/80 mu m (FBG2). FBG2 is chemically etched to reduce the cladding diameter which significantly enhances the pressure sensitivity. The shift of the Bragg wavelength in response to applied pressure is monitored with an optical spectrum analyser (OSA). The measured pressure sensitivity of FBG2 and FBG1 are found to be 5.85 x 10(-2) MPa-1 and 2.07 x 10(-2) MPa-1, which are approximately 18870 and 6677 times respectively higher than that can be sensed with a bare FBG. A very good linearity is observed between Bragg wavelength shift and pressure. This compact, low cost and robust design of the sensor can find applications in the areas of low and medium pressure measurement.