Investigation on growth and spectroscopic properties of Nd3+, Ho3+ co-doped KPb2Cl5 single crystal for laser application

The Nd,Ho:KPb2Cl5 single crystal was successfully grown by the Bridgman method for the first time. The absorption spectrum, fluorescence spectra, and fluorescence lifetimes were investigated under 808 nm laser diode (LD) excitation. Based on the Judd-Ofelt theory, the radiation properties of Ho3+ ions were thoroughly investigated. The Ωi (i=2,4,6) parameters were fitted as 7.758×10−20, 2.413×10−20, and 0.395×10−20 cm2, respectively. Intense infrared emission bands were observed with the peaks at 2002, 2852.5, and 3910 nm. The fluorescence lifetimes of the 5I7, 5I6, and 5I5 energy levels of Ho3+ ions were determined to be 9.435, 1.640, and 0.810 ms, respectively. The visible upconversion emissions were also observed in the Nd,Ho:KPb2Cl5 crystal excited by 808 nm LD. The energy transfer processes between Nd3+ and Ho3+ ions were discussed in detail. All results demonstrate that the Nd,Ho:KPb2Cl5 crystal has great potential as a gain medium for mid-infrared lasers.