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

Abstract

For over the past two decades it has been believed that the intense orange-red photoluminescence in Bismuth-doped materials originates from Bi$$^{2+}$$ 2 + ions. Based on the results from magnetic circular polarization experiments, we demonstrate that this hypothesis fails for Bismuth-doped silica glasses. Our findings contradict the generally accepted statement that the orange-red luminescence arises from $$^{2}P_{3/2}(1)$$ 2 P 3 / 2 ( 1 ) $$\rightarrow$$ → $$^{2}P_{1/2}$$ 2 P 1 / 2 transition in a divalent Bismuth ion. The degree of magnetic circular polarization of this luminescence exhibits non-monotonic temperature and field dependencies, as well as sign reversal. This complex behaviour cannot be explained under the assumption of a single Bi$$^{2+}$$ 2 + ion. The detailed analysis enables us to construct a consistent diagram of energy levels involved in the magneto-optical experiments and propose a new interpretation of the nature of orange-red luminescence in Bismuth-doped silica glass. A centre responsible for this notorious photoluminescence must be an even-electron system with an integer total spin, presumably a dimer of Bismuth ions or a complex consisting of Bi$$^{2+}$$ 2 + and an oxygen vacancy.

Understanding the ultraviolet, green, red, near infrared and infrared emission properties of bismuth halide double perovskite

“…5,9 The first authors 9 did not report UV emission but instead observed some emission bands between 500–800 nm. These bands and similar ones in other systems, were subsequently associated with the spin–orbit 2 P 1/2 and 2 P 3/2 (1,2) levels of the 6s 2 6p configuration of Bi 2+ , 11–13 to Bi 3+ pairs or clusters, 9 charge transfer transitions, radiative decay of self-trapped excitons, 14,15 Bi 3+ -defect emission, bismuth-oxygen species, 6 and other sources. 16 Furthermore, near infrared (NIR) emission bands with millisecond or sub-millisecond lifetimes have been associated with Bi 0 and Bi + .…”

“…The reader is referred to reviews showing the current interest in bismuth species which not only present literature data but also comment upon the difficulties in spectral interpretation. 3,13,16,17,19,36,37 The elpasolite Cs 2 NaBiCl 6 crystallizes in the Fm3 ˉm space group at RT, with Na + and Bi 3+ ions each surrounded by six Cl − ions to form [NaCl 6 ] 5− and [BiCl 6 ] 3− octahedra, whereas Cs + ions are 12-coordinated (Fig. 1b).…”

“…The reader is referred to reviews showing the current interest in bismuth species which not only present literature data but also comment upon the difficulties in spectral interpretation. 3,13,16,17,19,36,37…”

Review of bismuth‐doped fibers used in O‐band optical amplifiers‐scientific challenges and outlook

“…Laguta et al. showed that the ground state of luminescence center was a magnetic singlet with effective spin of 0, proving that Bi 2+ was not the BAC in bismuth‐doped silica glass 43,44 . This finding is also supported by crystal field modeling 45 .…”

“…In bismuth‐doped pure silica fibers, only Bi‐O‐Si linkages are expected to form 19 . The luminescence‐related bismuth species are identified as ions, serving as structural modifiers 20 . With phosphorous doping, Bi‐O‐P is also formed 21 .…”