Power loss characteristics of a sensing element based on a grooved polymer optical fiber under elongation

This study conducts a numerical and experimental investigation into the effects of elongation on the power attenuation characteristics of grooved polymer optical fibers (POFs). POFs with groove depths ranging from 0 to 1.1 mm are tensile tested. The load-elongation data are then used to compute the corresponding average plastic energy density (APED). An elastic-plastic three-dimensional finite element model is used to simulate the deformation which takes place near the grooved region of the elongated POF in order to clarify the experimental results. In general, the results show that the change rate of the power ratio or the sensitivity increases with increasing elongation and increasing groove depth. By applying a curve-fitting technique, an empirical expression is developed to relate the power ratio to the APED and the groove depth. It is found that the difference between the predicted values obtained from the proposed equation and the experimental results is less than 7%, thus confirming the APED to be a meaningful index with which to evaluate the sensitivity of POF sensors.