Efficient 2.0 μm emission in Nd3+/Ho3+ co-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 glasses for mid-infrared laser applications
Highlights: • The Ho{sup 3+} and Nd{sup 3+}/Ho{sup 3+} co-doped glasses were prepared by melt quenching method. • Nd{sup 3+} ions act as a good sensitizer for getting intense emission around at ∼2.0 μm. • The (σ{sup M}{sub emi}) emission cross-section has been found to be 3.85 × 10{sup −21} cm{sup 2}. • The energy transfer efficiency has been reached 50% from Nd{sup 3+} to Ho{sup 3+} ions. • The present glasses could be potential medium for ∼2.0 μm mid-infrared applications. - Abstract: Nd{sup 3+}/Ho{sup 3+} co-doped SiO{sub 2}-Al{sub 2}O{sub 3}-Na{sub 2}CO{sub 3}-SrF{sub 2}-CaF{sub 2}-Ho{sub 2}O{sub 3}-Nd{sub 2}O{sub 3} oxyfluorosilicate glasses have been prepared by high temperature melt-quenching method. The co-doped samples exhibit fluorescence bands centered at 892, 1058, 1330 nm and 2.0 μm under the excitation of 808 nm laser diode (LD). The energy transfer mechanism between Nd{sup 3+} and Ho{sup 3+} was analyzed based on the absorption, emission and the energy level structures of Nd{sup 3+} and Ho{sup 3+} ions. In the present investigation, the energy transfer efficiency from Nd{sup 3+} to Ho{sup 3+} reached ∼50% under the excitation of 808 nm. This result indicates that Nd{sup 3+} ions can be potentially used as sensitizers for Ho{sup 3+} ions to stimulate the NIR emissions. Stimulated emission cross-section was evaluated for the prominent {sup 5}I{sub 7} → {sup 5}I{sub 8} transition of Ho{sup 3+} ion by using the Mc-Cumber theory. The spectroscopic characteristics of Nd{sup 3+}/Ho{sup 3+} co-doped oxyfluorosilicate glasses are found to be suitable as optical medium for mid infrared emission at ∼2.0 μm.