Interferometric fiber-optic bending/nano-displacement sensor using plastic dual-core fiber.

We demonstrate an interferometric fiber-optic bending/nano-displacement sensor based on a plastic dual-core fiber. The light coupled into the two fiber cores is first guided along the fiber, and then reflected by the mirror coated at the fiber end. Reflected light coming out of the fiber produces interference that shifts as the fiber bends. The interference shift is interrogated using a slit and a photodetector. The resolution of our sensor is ∼3×10(-4) m(-1) for sensing the bending curvature, and ∼70 nm for sensing the displacement.