A Sensing Element Based on a Bent and Elongated Grooved Polymer Optical Fiber

Wei-Hua Lu,Li-Wen Chen,Wen-Fu Xie,Yung-Chuan Chen

doi:10.3390/s120607485

Abstract

An experimental and numerical investigation is performed into the power loss induced in grooved polymer optical fibers (POFs) subjected to combined bending and elongation deformations. The power loss is examined as a function of both the groove depth and the bend radius. An elastic-plastic three-dimensional finite element model is constructed to simulate the deformation in the grooved region of the deformed specimens. The results indicate that the power loss increases significantly with an increasing bending displacement or groove depth. Specifically, the power loss increases to as much as 12% given a groove depth of 1.1 mm and a bending displacement of 10 mm. Based on the experimental results, an empirical expression is formulated to relate the power loss with the bending displacement for a given groove depth. It is shown that the difference between the estimated power loss and the actual power loss is less than 2%.

Highlights

The power delivered to the polymer optical fibers (POFs) specimen with no groove prior to elongation was measured in advance and denoted as Pin (33 μW)
The Pin value is affected by the relative humidity (RH), according to our experiment results, the variation of power ratio Pout/Pin with bend and elongation is independent of the RH
The results have shown that the power loss increases significantly with an increasing bending displacement or groove depth, but is insensitive to the bending radius

Summary

Introduction

Compared to conventional glass fibers, polymer optical fibers (POFs) have a larger core diameter, greater flexibility, lighter weight, and a lower cost [1], and as a result, POFs have attracted intensiveSensors 2012, 12 interest for sensing applications in recent years [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18]. Arrue et al [2] showed that the power loss induced in bent POFs increases as the bend radius is reduced. Lomer et al [4] developed a quasi-distributed system for level sensing based on a bent side-polished POF cable. Kulkarni et al [6] developed a novel POF sensor for weight measurement applications and showed that the sensitivity could be enhanced by increasing the corrugation pitch of the deforming plates used within the sensor structure. Babchenko and Maryles [7] presented a displacement sensor based on a bent imperfected POF. Kuang et al [9] developed a POF displacement sensor based on dual cycling bending and showed that the sensitivity could be enhanced by increasing the number of rollers or decreasing the interval between the rollers

Methods

Results

Conclusion