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Na 5 Lu 9 F 32 single crystals co-doped with various Er 3+ /Yb 3+ 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 Na 5 Lu 9 F 32 single crystals are obtained from the measured transmission and Raman spectra, respectively. The Judd-Ofelt parameters of Er 3+ in the obtained crystal was calculated and discussed according to the measured absorption spectra. Compared with the Er 3+ single-doped Na 5 Lu 9 F 32 crystal, an obviously enhanced emission band at 1500 nm was observed upon excitation of 980 nm laser diode (LD) via energy transfer from Yb 3+ to Er 3+ . Decay curve fitting using a Inokuti-Hirayama expression indicates dipole-dipole energy transfer from Yb 3+ to Er 3+ .The maximum emission cross section at ∼1.5 μm was also calculated to be 10.12 × 10 −20 cm 2 for the Na 5 Lu 9 F 32 single crystal of 1% Er 3+ and 6% Yb 3+ in molar fraction doping concentration. [ABSTRACT FROM AUTHOR]