Infrared luminescent properties of Na5Lu9F32 single crystals co-doped Er3+/Yb3+ grown by Bridgman method

Abstract

Na5Lu9F32 single crystals co-doped with various Er3+/Yb3+ concentrations were grown by an improved Bridgman method for the first time. The crystal structure is characterized by means of X-ray diffraction (XRD). High transmission in the range from 400 nm to 7150 nm and maximum phonon energy about 441 cm−1 for the Na5Lu9F32 single crystals are obtained from the measured transmission and Raman spectra, respectively. The Judd-Ofelt parameters of Er3+ in the obtained crystal was calculated and discussed according to the measured absorption spectra. Compared with the Er3+ single-doped Na5Lu9F32 crystal, an obviously enhanced emission band at 1500 nm was observed upon excitation of 980 nm laser diode (LD) via energy transfer from Yb3+ to Er3+. Decay curve fitting using a Inokuti-Hirayama expression indicates dipole-dipole energy transfer from Yb3+ to Er3+.The maximum emission cross section at ∼1.5 μm was also calculated to be 10.12 × 10−20 cm2 for the Na5Lu9F32 single crystal of 1% Er3+ and 6% Yb3+ in molar fraction doping concentration.