Broadband photoluminescence of Bi₂O₃-GeO₂ binary systems: glass, glass-ceramics and crystals

Ultra-broadband emission covering 1000-1800 and 1800-3020 nm of Bi ₂O₃-GeO₂ binary system materials, from glass to glass-ceramics to crystals, is presented in this paper. This is the first time, to our best knowledge, that broadband photoluminescence of BGO crystals (including Bi₄Ge₃O₁₂ and Bi ₁₂GeO₂₀) in the range of 1800-3020 nm has been realized. HRTEM, XPS and XANES have been used to investigate the effects of the valence states and the structure environment of bismuth on the emission properties of Bi₂O₃-GeO₂ binary system materials. Bi ²⁺ and Bi⁺ are proposed as the emission centers of the photoluminescence peaks at 1060 and 1300 nm, respectively. The broadband emission from 1800 to 3020 nm originates from bismuth clusters. Bi ₂O₃-GeO₂ binary system materials could be promising laser materials in the field of full-band optical fiber communication amplifiers, ultra-fast lasers and diode pumped solid state lasers, due to their broadband emission spectra and their feasibility of synthesis and drawing into fibers.