Efficient 2.0 μm emission in Nd3+/Ho3+ co-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 glasses for mid-infrared laser applications

Abstract Nd 3+ /Ho 3+ co-doped SiO 2 -Al 2 O 3 -Na 2 CO 3 -SrF 2 -CaF 2 -Ho 2 O 3 -Nd 2 O 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 3+ and Ho 3+ was analyzed based on the absorption, emission and the energy level structures of Nd 3+ and Ho 3+ ions. In the present investigation, the energy transfer efficiency from Nd 3+ to Ho 3+ reached ∼50% under the excitation of 808 nm. This result indicates that Nd 3+ ions can be potentially used as sensitizers for Ho 3+ ions to stimulate the NIR emissions. Stimulated emission cross-section was evaluated for the prominent 5 I 7  →  5 I 8 transition of Ho 3+ ion by using the Mc-Cumber theory. The spectroscopic characteristics of Nd 3+ /Ho 3+ co-doped oxyfluorosilicate glasses are found to be suitable as optical medium for mid infrared emission at ∼2.0 μm.