Multifunctional tunable ultra-broadband visible and near-infrared luminescence from bismuth-doped germanate glasses

Abstract

Here, we present three facile approaches to achieve wavelength tunable luminescence in the same host material with single dopant, i.e., by modulating doping level, preparation temperature, and atmosphere. Based on these methods, ultra-broadband tunable near-infrared luminescence with the largest full width at half maximum of about 500 nm covering the whole windows of optical communication has been obtained in bismuth-doped germanate glasses. Wavelength tunable luminescence is also observed with the change of excitation wavelength. Systematical strategy was followed to approach the physical origin of the near-infrared luminescence and we proposed that three different bismuth active centers contribute to the near-infrared luminescence in the germanate glasses. A comprehensive explanation for the tunable luminescence is given, combining the concentration, energy transfer, and chemical equilibrium of these active centers in the glasses. With the increase of melting temperatures and the increase of reducing extent of the preparation atmosphere, bismuth species transform from Bi 3þ to Bi 2þ , Bi þ , Bi 0 and bismuth clusters, and then to bismuth colloid. Of particular interest is that red tunable luminescence was also observed by modulating doping level, preparation atmosphere, and excitation wavelength. Besides, the trapped-electron centers in germanate glasses can interact with bismuth species of high valence states leading to the formation of bismuth active centers of low valence states and the decrease of trapped-electron centers. This tunable ultra-broadband luminescence is helpful for a better understanding of the origin of the near-infrared luminescence in Bi-doped glasses and may have potential applications in varieties of optical devices. V C 2013 American Institute of Physics. [http://dx

Ultra-broadband infrared luminescence of Bi-doped thin-films for integrated optics

“…Finally, the different luminescence properties of glasses and films could be understood. For glasses, some factors like the redox of Bi species during melting, the different oxidization environment in different micro-areas during casting, may play important role in the formation of Bi species, resulting in the co-existence of several kinds of BIA with different characteristics [14]. By contrast, for the film prepared under certain P O2 in this work, all Bi species undergo quite similar oxidization environment, thus BIA in the specific film has similar feature.…”

“…While the film deposited under 12.0 Pa shows three bands at around 276, 312 and 533 nm. All these PLE spectra are distinct from those of as-made glass [14]. Fig.…”

“…As the excitation wavelength is changed from 300 to 980 nm, the emission peak position has a large shift in the range of 1080~1330 nm. The observation is possibly due to the co-existence of several different Bi infrared active centers (BIA) [14]. .…”

“…Meanwhile, germanate glasses have high refractive index, low phonon energy, excellent transparency in the infrared region, and Bi-doped germanate glasses own high NIR luminescence efficiency with large full-width at half maximum (FWHM) [14,15]. Here, we report on the PLD deposition of Bi-doped germanate glass films grown on various substrates, including LaAlO 3 , GaAs, Si, and silica.…”

Enhanced broadband near-infrared luminescence in Bi-doped glasses by co-doping with Ag

“…1(b). As previously reported, when the temperature is above 1000 C, Bi 3þ ions of Bi 2 O 3 will transform to Bi species of lower valence states by the auto-thermo reduction 21 as follows: 23 while Bi atom clusters and metals have absorption at around 465 nm. 25,26 Thus, with the reduction of Ag þ , the decrease of the absorption at around 465 nm and the increase of the absorption in 560-1000 nm reveal the oxidization of some Bi atom clusters and colloid into some kinds of BNIA.…”