R(2)O(3) (R = La, Y) modified erbium activated germanate glasses for mid-infrared 2.7 μm laser materials

Er(3+) activated germanate glasses modified by La(2)O(3) and Y(2)O(3) with good thermal stability were prepared. 2.7 μm fluorescence was observed and corresponding radiative properties were investigated. A detailed discussion of J–O parameters has been carried out based on absorption spectra and Judd–Ofelt theory. The peak emission cross sections of La(2)O(3) and Y(2)O(3) modified germanate glass are (14.3 ± 0.10) × 10(−21) cm(2) and (15.4 ± 0.10) × 10(−21) cm(2), respectively. Non-radiative relaxation rate constants and energy transfer coefficients of (4)I(11/2) and (4)I(13/2) levels have been obtained and discussed to understand the 2.7 μm fluorescence behavior. Moreover, the energy transfer processes of (4)I(11/2) and (4)I(13/2) level were quantitatively analyzed according to Dexter’s theory and Inokuti–Hirayama model. The theoretical calculations are in good agreement with the observed 2.7 μm fluorescence phenomena. Results demonstrate that the Y(2)O(3) modified germanate glass, which possesses more excellent spectroscopic properties than La(2)O(3) modified germanate glass, might be an attractive candidate for mid-infrared laser.