The effect of co-doping Y3t and the doping concentration of Nd3t on the spectroscopic properties and laser performance of Nd:CaF2 crystals are investigated systematically. For a 0.5% Nd:CaF2 crystal, the emission lifetime at 1.06 μm increases from 18 to 361 μs by co-doping 10 at.% Y3t, while the emi