Broadband NIR emission from multiple Bi centers in nitridated borogermanate glasses via tailoring local glass structure

Bi-Doped photonic materials with broadband near infrared (NIR) photoemission have allowed rapid progress of new-generation fiber lasers and super-broadband optical amplifiers. Despite this, major challenges persist towards realizing super-broad and efficient Bi NIR emission covering the whole telecommunication window due to the complicated luminescence behavior, especially for glasses doped with a low Bi content. Here, via introducing nitride into glasses, we obtained super-broad and highly reinforced NIR emission in multi-component borogermanate glasses, which resulted from the generation of multiple Bi NIR-active centers. The spectral bandwidth exceeded approximate to 600 nm; this enabled Bi-activated glasses to cover the whole NIR region (850-1700 nm), which can hardly be realized by quantum-dot-doped glasses, rare earth-functionalized glasses or current Bi-doped multi-component photonic glasses. A detailed analysis of the spectra and tailoring of local glass structures revealed that the compact glass structure with the addition of antimony oxide and the bonding effect of nitrogen could contribute to significant increase in the Bi NIR emission intensity and decay lifetime. The newly generated Bi luminescent centers may have originated from the low-valence Bi effected by oxygen vacancies. These results will add new knowledge to the luminescence behaviors of Bi and may help solve the current limitations of Bi-doped glass and fiber materials. Moreover, the nitridation of materials may offer a way to fundamentally boost luminescence efficiency, especially for ultra-low activator content.