Er³⁺ -doped fiber laser sensor design for structural health monitoring applications

Fiber optic sensors are a mature choice for highly sensitive applications. Most modern pressure sensors are based on the piezoelectric effect (pressure causes a material to conduct electricity at a certain rate, leading to a specific level of charge flow associated with a specific level of pressure). In this paper, we describe theoretical calculations which predict encouraging experimental results on pressure sensing with optical fibers. These results may be used in applications for distributed sensors in structural health monitoring (SHM). The sensing fiber is capable of propagating 3 modes with a straight fiber length of 30cm at a lambda of 1550nm. In our experiments, a perpendicular force of F=200gr cause a core compression of nearly 2um, according to Poisson's elastic coefficient for silica, which in turn provoked the loss of half the number of modes indicating a 50% sensitivity as shown in our results included here. The proposed set-up intends to measure force vs propagating modes in a standard single mode fiber. A full set of results will be included in our presentation.