Optical Properties and Bismuth Redox in Bi-Doped High-Silica Al–Si Glasses

Abstract

Due to their unique optical properties, Bi-doped glasses have a great potential for the development of new tunable laser sources. Particular attention is given to high-silicate Bi-doped glasses as active media for fiber lasers and optical amplifiers, capable to operate at the second and the third near-infrared (NIR) transparency windows. Although significant practical advances have been achieved in this area, the origin of the NIR luminescence remains unclear. In the present paper, a set of glasses 95.5SiO 2 −4.5Al 2 O 3 −xBi 2 O 3 (x = 0; 0.005; 0.01; 0.05; 0.1; 0.2) were synthesized using a conventional meltquenching technique and investigated using a multiscale approach. Variation of the NIR emission was correlated with the change of other optical properties, structure and bismuth redox, supported by fluorescence/absorption, Raman, and XANES experimental studies, respectively. It was found that redox of bismuth shifted toward the formation of more reduced Bi species with the decrease of the dopant level. Based on the complementary experimental results, the two NIR optical centers observed were attributed to the presence of a Bi + ion, which dominates at the lowest dopant level, and presumably a Bi + −Bi + dimer, forming at higher Bi concentrations. The dimer center was found to participate in a Forster-type energy transfer, interpreted as energy migration. This knowledge complements previous findings and will help in rational engineering of Bi-doped optical materials.

The riddle of orange–red luminescence in Bismuth-doped silica glasses

“…This PL was demonstrated for the first time in bulk sintered fibre preforms fabricated from nano-porous xerogels 35 . Later, this luminescence was attributed to a single Bi ion by analogy with the work of Blasse et al 2 and at present, to the best of our knowledge, this is a generally accepted interpretation 28 , 36 – 38 .…”

Impact of ZnO Addition on Er3+ Near-Infrared Emission, the Formation of Ag Nanoparticles, and the Crystallization of Sodium Fluorophosphate Glass

“…where τ (s) is effective time and β (dimensionless) is a constant ranging from 0 to 1. The stretched exponential behavior can originate from different microscopic mechanisms, in particular, for the glasses it can be an evidence of a disorder in the optical center environment [26,27]. In this case, the β parameter can be considered as a mere of this disorder: β = 1 corresponds to a single-exponent decay and no variation of the site, whereas a decrease in β indicates higher dispersion in the local environment of the optical center.…”

Introductory Chapter: Bismuth-Related Optoelectronic Materials

“…So there often co-exist many types of Bi ions or BAC in Bi-doped materials [50]. Though the full control of the formation of BACs is very hard, reductive agents, like high-purity silicon powder or sucrose in MCVD process [51] and SiC in melt and pour glass [52] have already been introduced in the fabrication of the Bi-doped materials as bismuth NIR emitting centers are formed in an endothermic redox chemical reaction [53]. In addition, post treatments, like femtosecond laser [54], thermal treatment [55,56], γ-radiation [57], H 2 reduction [58], etc.…”