Large-core hollow fibers for speckle-based displacement sensing

We study the application of a large-core hollow fiber as a platform for displacement sensing. The sensor is assembled by inserting and appropriately moving a single-mode fiber in the empty core of the hollow fiber. Such a construction allows attaining a speckled intensity profile at the hollow fiber output, which is evaluated while one controllably displaces the single-mode fiber in its interior. Our results allow identifying this scheme as a promising means for exploring the multimode characteristics of hollow fibers in sensing contexts.