“…For example, Nd 3+ :KGd(WO 4 ) 2 is an excellent laser material medium [16,17]. Recently, the preparation and spectral properties of Yb 3+ -doped other compounds were also reported, such as YbAl 3 (BO 3 ) 4 , Yb 3+ -doped Ca 4 NdO(BO 3 ) 3 , Yb 3+ -doped M 1 M 2 (PO 4 ) 2 (M 1 = Na, Rb; M 2 = Lu, Y) and so on [18][19][20][21][22][23][24][25]. Although the spectral properties of above mentioned materials were reported, it is still necessary to explore new more efficient Yb 3+ -doped laser material.…”