Impurity-doped fiber-optic shock position sensor

We have demonstrated the operation of a fiber-optic device originally proposed to continuously measure the location of a shock front, but which also has potential for use as a crack location sensor. It consists of one or a group of fibers uniformly doped along their length with neodymium, which fluoresces at about 1060 nm in response to being optically pumped at a shorter wavelength. In our case, the pump source was a laser diode emitting at 810 nm. As the length of the fiber is reduced, the strength of the fluorescence signal diminishes along with the number of fluorescing atoms. Laboratory and explosives experiments were performed on sensor fibers containing various concentrations of dopants. We also investigated the benefits, in an explosives application, of adding phosphorus to narrow the fluorescence line