A simple Fabry-Perot pressure sensor fabricated on fiber optic tip

In this work, we demonstrate an extrinsic pressure sensor realized on single mode fiber tip by means of simple fabrication steps and with low-cost instrumentations. The sensing element consists in a Fabry-Perot cavity: one reflecting surface is the end of the optical fiber, precisely cut, and the other one is a metallic diaphragm. Under the action of the external pressure, the metallic diaphragm bends changing the optical cavity length and, consequently, the characteristics of the reflected signal. The holder structure, which allows the alignment of the fiber tip and reflecting diaphragm, consists in a commercial zirconia ferule with external diameter of Dex = 2.5 mm. Despite its simplicity and cost-effectiveness, the achieved results show performance comparable to more complex and expensive configurations. By using an aluminum plate as reflecting diaphragm. sensitivity ranging in the 70-130pm/mmHg is experimentally.