Novel constructions of optical fibers doped with rare – earth ions

In the paper the research on rare-earth doped and co-doped optical fibre conducted in the Laboratory of Optical Fiber Technology at the Bialystok University of Technology is presented. Novel active fibre constructions like multicore, helical-core and side detecting ribbon/core optical fibers were developed with a targeted focus into application. First construction i.e. multicore RE doped optical fibers enable supermode generation due to phase - locking of laser radiation achieved in a consequence of exchanging radiation between the cores during the laser action. In the paper a far - field pattern of 19 - core optical fiber-doped with Yb3+ ions, registered in the MOFPA system, showed centrally located peak of relatively high radiation intensity together with smaller side-lobes. Another new construction presented here is helical-core optical fibers with the helix pitch from several mm and the off-set ranging from 10 μm to 200 μm. The properties of helical-core optical fiber co-doped with Nd3+/Yb3+ were also discussed. In the field of sensor applications novel construction of a sidedetecting luminescent optical fiber for an UV sensor application has been presented. The developed optical fiber with an active core/ribbon, made of phosphate glass doped with 0.5 mol% Tb3+ ions, was used as a UV sensing element.