Characterization of Optical Fibers Directly Embedded on Metal Using a Particle Spray-Based Method

The surface mounting or embedding of optical fibers into a substrate is of great importance for optical fiber sensing. Although techniques are well developed for certain types of material, bonding fibers onto metallic materials remains a challenge. Current methods usually expose the fiber to extreme conditions during the fabrication process, meaning that special coatings are necessary to protect the fiber. In this paper an additive manufacturing method incorporating a high velocity oxygen fuel (HVOF) zinc particle spray, was used to directly embed optical fibers with standard and hard acrylate coatings onto a stainless-steel plate. The method was experimentally proven to have no significant influence on the light guiding conditions of the fiber and introduce no extra loss. This was achieved without the need for applying a protective layer to the fiber prior to the embedding process. In addition, the thermal response of the mounted fiber is investigated theoretically and experimentally. Using optical frequency domain reflectometry, we demonstrate that the thermal expansion of the metal plate enhances the temperature sensitivity of the fiber by nearly a factor of three. The theoretical analysis agrees very well with the experimental results.