Efficient 2 μm emission in Er3+/Ho3+ co-doped lead silicate glasses under different excitations

Er3+ has been considered one of the most suitable sensitive ions of Ho3+ to generate 2 μm emission. In this work, luminescent properties and energy transfer mechanism of Er3+/Ho3+ co-doped lead silicate glass were systematically investigated under 980 and 1550 nm excitations, respectively. Based on the absorption spectra, the Judd-Ofelt intensity parameters, absorption and emission cross sections, and gain coefficient were calculated. The emission cross section of Ho3+: 5I7 → 5I8 transition is as large as 8 × 10−21 cm2. And the calculated maximum gain coefficient is 3.48 cm−1 at 2010 nm. In addition, the energy transfer efficiency between Er3+: 4I13/2 level and Ho3+: 5I7 level can reach 89.3% when the samples were pumped by a 980 nm laser diode. An intense 2 μm emission was obtained upon excitation of 1550 nm due to the large absorption cross section of Er3+ at 1550 nm and efficient energy transfer from Er3+: 4I13/2 level to Ho3+: 5I7 level. These results suggest that the Er3+/Ho3+ co-doped lead silicate glass has great potential for application as a mid-infrared laser material.