Structured blue emission in Bismuth doped fibers

We report an experimental investigation of the photoluminescence (PL) activities detected in as-drawn and γ-ray irradiated samples of a microstructured optical fiber elaborated with a silica-based core doped with Bismuth ions. The presence of several visible emission bands is revealed and characterized under 325 nm laser excitation. In both samples, four narrow emission bands are studied and analyzed. They are similarly bleached by a long UV laser exposure times. In addition, time-resolved luminescence data show that all these bands possess a similar lifetime of ∼4 μs Data analysis indicated that the energy levels scheme of the point defects responsible for these bands consists of: one above 5 eV, one at ∼3.6 eV, and at least one in the range 2.6–2.8 eV and of the ground one. As a consequence, even if the exact structural model cannot yet be fully identified, we suggest that the bands originate from color centers related to the Bismuth ions.