Characterization of a nanoparticles-doped optical fiber by the use of optical backscatter reflectometry

摘要

The use of nanoparticles is gaining large interest in modern photonic technology, mainly because nanoparticles can drastically change the properties of optical media. Here, a custom special fiber has been considered for investigation. The fiber presents a co-doped erbium and magnesium oxide nanoparticles core, and standard telecommunication size. Modified Chemical Vapor Deposition technique, together with the spontaneous phase separation, permits to grow inside the core a random distributed pattern of nanoparticles, whose size varies between 20 to 100 nm, considering the transversal section. The nanoparticle increases the scattering, which is, in general, an unwanted occurrence. Nevertheless, interesting applications can emerge in sensor field. In this work the focus has been concentrated on the distributed sensing applications offered by the enhanced backscattering. The fiber has been characterized by the use of an Optical Backscatter Reflectometer (OBR) Luna 4600. Results show that the intensity of backscattering, induced by the nanoparticles, is 50 dB larger than the one shown by standard single mode fiber. This results in an exponential decay of the reflected optical power, which vanish after 1.7 meter of propagation. Moreover, using the OBR. it has been possible to characterize the polarization properties of this special fiber. Because the nanoparticles are stretched during the drawing process, the fiber presents a well-defined polarization signature pattern, with a random alternation of polarization state every, roughly, 10 cm. These properties are promising for creating a distributed, high reflectivity, sensors, in application like OBR spatial multiplexing.