Fiber optic Fabry Perot pressure sensor based on commercial ferule

In this study, we show an extrinsic pressure sensor consisting in a Fabry-Perot cavity realized on single mode fiber tip. The first mirror is given by the end of the optical fiber, that accurately cut, acts as reflecting mirror. The other one is made of a thin and elastic metallic diaphragm. Stressed by an external pressure, the metallic diaphragm bends, changing the optical cavity length and, therefore, the characteristics of the reflected signal. The holder structure, which allows the alignment of the fiber tip and reflecting diaphragm, is a commercial zirconia ferrule with external diameter of D_ex = 2.5 mm. Although its construction procedure results simple and cheap, the results show performance comparable to more complex and expensive configurations. By using an aluminium plate as reflecting diaphragm of 100 μm thickness, sensitivity ranging in the 70-130pm/mmHg is experimentally demonstrated.