Effect of optical basicity on broadband infrared fluorescence in erbium-doped germanate glasses

► Influence of optical basicity on emission spectra at 1.55 μm of Er3+ ions were investigated in alkali and alkaline earth germanate glasses. ► The bandwidth and intensity of emission spectra at 1.55 μm of Er3+ depend on the optical basicity of the host glasses irrespective of the glass systems. ► The optical basicity calculated from glass composition may work as a guiding principle to obtain broadband fiber amplifier for wavelength division multiplexing systems.