Long-period fiber grating bending sensors in laminated composite structures

In this paper, we present the experimental results of the effect of bending an over-written long-period fiber grating (LPG) on the transmitted power spectrum and total transmitted power of a light-emitting diode (LED). It is found that the total transmitted power through the LPG decreases linearly with bend curvature within the range from 0 to about 0.001/mm. The-error for determining the bend curvature due to the actual non-linearity of the sensor is estimated to be +/- 2x 10(-5)/mm. Therefore, a simple power measurement scheme using an embedded LPG can be employed to measure the static bend curvature and dynamic process of structures.