The origin of the heterogeneous distribution of bismuth in aluminosilicate laser glasses

Abstract

As one kind of novel and burgeoning laser materials, bismuth‐doped silicate glasses have aroused increasing attention for the super broadband near‐infrared (NIR) emission. However, the large optical scattering loss, resulting from optical heterogeneity in glass color and refractive index, limits their further applications in telecommunication system. Thus, it is urgent to uncover the essence of heterogeneity in Bi‐doped silicate glasses and subsequently improve glass optical performance. It will give us some hint to homogenize the glass component and Bi active centers so as to boost the development of Bi‐based glass materials. Here, taking 1 typical Bi‐doped calcium aluminosilicate glass as an example, we revealed the origin of the optical heterogeneities in glass color and refractive index through the NIR emission spectra, electron probe microanalyzer (EPMA) of elements and X‐ray photoelectron spectroscopy (XPS) of Bi 4f5/2, Bi 4f7/2, and Al 2p. The inhomogeneous distribution of Bi and aluminum components is responsible for the heterogeneity in this glass system. In addition, we found that tetrahedral coordinated aluminum favors the existence of Bi NIR centers, consequently resulting in enhanced Bi NIR emissions. Furthermore, based on our results and the role of Al3+ in glass network, we demonstrate the homogenizing of glass component by finely tuning glass composition. This work will enrich the understanding of Bi‐doped laser glass and provide a guideline for the design of component‐derived Bi‐doped silicate glasses and fibers with efficient NIR emission and high optical quality.

Regulating the Bi NIR luminescence behaviours in fluorine and nitrogen co-doped germanate glasses

“…According to previous reports, the emission bands at ~924 and 1496 nm can be attributed to the new Bi-activated centers generated by the addition of nitride in germanate glass, 22,23,34 while the emission band at ~1150 nm originates from the typical transition 3 P 1 → 3 P 0 of Bi + . 20,35 Moreover, as shown in Fig. 2(a), the integral intensity of ~1150 nm emission band shows a dramatical decreasing trend as the radius of alkaline earth ion increases, while the integral intensity of ~924 and ~1496 nm emission bands gets slightly enhanced.…”

Enhanced NIR photoemission from Bi‐doped aluminoborate glasses via topological tailoring of glass structure

“…Previous reports indicate that local glass structure, especially the coordination of Al species, plays a vital role in modulating Bi NIR emission, including emission intensity and decay behaviors . Therefore, fully understanding the local glass structure will help us to comprehend the mechanism for this highly improved Bi NIR emission.…”

Ultrabroad Photoemission from an Amorphous Solid by Topochemical Reduction

“…Thus, detailed information on glass local structure with addition of SiC is essential to gain insight into the mechanism for the evolution of Bi NIR emission. Before this, we checked the uniformity qualitatively for correct interpretation of results, which is also an essential in evaluating the performance of Bi‐doped glass, as doping Bi into glasses tends to result in the deterioration of glass quality and inaccurate test results . As presented in Figure , Ge, Al, Ca, and O elements are homogeneously distributed on the micrometer scale in glass matrix and no pronounced heterogeneities zone is observed.…”

“…Though transition‐metal‐doped glass ceramics and quantum‐dot‐doped glasses offer a way to achieve broadband emission, limited success has been achieved . Specially, the technically relevant C‐ and L‐bands (1530–1625 nm) of the telecommunication window, which is extremely significant and urgent for increasing the communication capacity, are still covered only by the tail of the material's NIR emission spectrum, with strongly decreasing emission intensity toward the red end of the band . Hence, it is essential to further spectrally extend the emission region, especially in the spectral range of 900–1600 nm, considering their promising applications in nowadays bioimaging and optical communication systems.…”

“…The traditional reducing agents, such as carbon, will react quickly at low temperatures and thus cannot effectively promote Bi NIR emission considering the high melting temperature of glasses (more than 1400 °C), especially under air atmosphere . Moreover, the homogeneity of glass sample obtained is also questionable …”