Highly Efficient Orange-Red Emission in Sm3+-Doped Yttrium Gallium Garnet Single Crystal

High-quality single crystals with empirical composition Y2.96Sm0.04Ga5O12 (YGG: Sm3+) were successfully prepared by the optical floating zone method for the first time and compared with related single crystals of Y2.96Sm0.04Al5O12 (YAG: Sm3+). With both crystals, XRD showed that Sm3+ entered the cubic-phase structure. Optical absorption spectra produced a series of peaks from Sm3+ in the 250 nm to 550 nm range, and photoluminescence excitation (PLE) spectra detected at 613 nm showed strong excitation peaks at 407 nm and 468 nm. A strong emission peak at 611 nm (orange-red light) was observed in the photoluminescence (PL) spectra under excitations at both 407 and 468 nm, respectively, but it was much brighter under excitation at 407 nm. Furthermore, with both emission spectra, the peaks from the YGG: Sm3+ crystal were significantly more intense than those from the YAG: Sm3+ crystal, and both experienced a blue shift. In addition, under excitation at 407 nm, the color purity of the emitted orange-red light of YGG: Sm3+ was higher than that of the YAG: Sm3+ crystal, and the fluorescence lifetime for the 4G5/2 → 6H7/2 transition of YGG: Sm3+ was longer than that of the YAG: Sm3+ crystal. The optical properties of the YGG: Sm3+ crystal are better than those of the YAG: Sm3+ crystal.