KXÌõwIî«xAE Er 3{ 1.5 mm ÑõAEÌÖW {¼÷Ec¨ÃvÞ ®Éq()¤C2218755 ¡ls_ÞìaeHò¬ 1150 Þ såwåw@lÔE«w¤ÈC6068501 ss ¶aegcñ{¼¬Emission spectra of Er 3{ ions at 1.5 mm band were measured in bismuthate, tellurite and silicate glasses. The bandwidth of the emission spectrum was well correlated to the optical basicity of the host glasses irrespective of the glass systems. This result indicates that the lower basicity of the host glass reduces the covalency between Er 3{ and oxide ions, and thus electron density of relevant vacant orbital of Er 3{ ions in glasses, resulting in the broader emission spectrum. It was found that the optical basicity calculated from glass composition may work as a guiding principle to obtain broadband fiber amplifier for wavelength division multiplexing systems.