Metallic and semi-conducting nano-particles were incorporated into and on the surface of optical fibers to form sensors and other optoelectronic devices on standard telecommunications grade optical fibers. Optical fibers provide a macroscopic platform to exploit the wide range of functionality inherent in nanostructures and nano-particles. Several ways of forming sensitive and robust chemical sensors, based on plasmon resonances of metallic islands and nano-particles, were demonstrated. These nano-particles were formed on tip or surface of the optical fibers by thermal or plasma arc annealing of very thin (4 -12 nm) gold films, that were deposited by electron beam deposition and sputtering. Development of in-line optical fiber structures, involving single mode or multimode optical fibers fused to an arrangement of coreless and graded index fibers, was also carried out. This enabled light propagating in the core of the optical fiber to expand to the surface of the coreless fiber and to effectively interact with nano-particles on the surface and the environment. Metallic and semiconducting nano-particles were also incorporated inside an optical fiber matrix and this could enable us to effectively characterize novel materials and possibly form optical switches. Moreover, these optical fiber sensors and devices were integrated into textile structures to explore the possibility of formation of optoelectronic textiles.