Analysis of energy transfer process based emission spectra of erbium doped germanate glasses for mid-infrared laser materials

• Er3+ doped germanate glass with good thermal stability were prepared.
• Ionic boding nature was proved by bonding parameter calculation.
• Mid-infrared fluorescent behaviors and energy transfer were investigated.
• Rate equation and Dexter’s theory were utilized to elucidate 2.7 μm emission.

Er3+ activated germanate glass with good thermal stability was prepared. Bonding parameters have been calculated and the nature of ionic bonding of the germanate glass has been determined. Mid-infrared fluorescence was observed and corresponding radiative properties were investigated. For Er3+:4I11/2→4I13/2 transition, high spontaneous radiative transition probability (30.09 s−1), large emission cross section ((14.84 ± 0.10) × 10−21 cm2) and superior gain performance were obtained from the prepared glass. Besides, energy transfer processes concerning the 2.7 μm emission were also discussed in detail. According to simplified rate equation and Dexter’s theory, energy transfer microscopic parameters were computed to elucidate observed 2.7 μm emissions. Results demonstrate that the prepared germanate glass possessing excellent spectroscopic properties might be an attractive candidate for mid-infrared laser or amplifier.