An Optical Fiber Pressure Sensor Based on Duralumin Grooved Plate

In this paper, a novel optical fiber pressure sensor based on duralumin grooved plate was experimentally demonstrated. The sensing structure consists of two duralumin plates, and uniform grooves were carved on the plates. The fiber was vertically placed between the plate grooves. Under different pressure conditions, there will be different micro-bending of the optical fiber, which will result in the modes conversion of the fiber. Some fiber modes become radiative modes, which will lead to the loss of transmission power in the fiber. We can make use of this special effect to fabricate optical fiber pressure sensor. We first tested the single mode fiber (SMF). By repeat applied cyclic pressure on the sensing structure, we recorded the changes of light power and obtained the sensitivity of 1.11 mW/kgf and 1.4 mW/kgf at 1550 nm and 1310 nm, respectively. In addition, we analyzed the spectral changes in the fiber and experimentally analyzed the temperature characteristics of the sensing structure, found that the sensor has good temperature stability. Moreover, because of its simple fabrication and highly adjustable property, this sensor is suitable for engineering application. We also use this duralumin grooved plate to test the few mode fiber (FMF), and found that due to a variety of core modes coupling in the fiber, the pressure sensing characteristics are not good. However, by analyzing its spectrum, we found that this device can achieve some special mode conversion and has a good application prospect.