Tm3+ and Nd3+ singly doped LiYF4 single crystals with 3-5 μm mid-infrared luminescence

Mid-infrared (MIR) emissions of 2.4 and 3.5 mu m from Tm3+:LiYF4 single crystals attributed to H-3(4) -> H-3(5) and H-3(5) -> F-3(4) transitions as well as MIR emissions of 4.2, 4.3, and 4.5 mu m from Nd3+: LiYF4 lasers attributed to I-4(15/2) -> I-4(13/2), I-4(13/2) -> I-4(11/2), and I-4(11/2) -> I-4(9/2) transitions, respectively, are observed. LiYF4 single crystals possess high transmittance of over 85% in the 2.5-6 mu m range. The large emission cross-sections of Tm-doped crystals at 2.4 mu m (1.9 x 10(-20) cm(2)) and Nd-doped crystals at 4.2 mu m (0.84 x 10(-20) cm(2)) as well as the high rare-earth doping concentrations, excellent optical transmission, and chemical-physical properties of the resultant samples indicate that Nd3+ and Tm3+ singly doped crystals may be promising materials for application in MIR lasers.