Growth and Spectral Properties of Er~(3+):LiYF_4 Single Crystal

Er3+:LiYF4 single crystal was grown by the Bridgman method under non-vacuum atmosphere.The single crystal was in size of φ9mm×68mm with 1mol% concentration of Er3+ ions.Optical properties of the single crystal in-cluding the refractive index,UV and IR transmission spectra,absorption spectrum,near-infrared emission spectrum under 980nm excitation and mid-infrared emission spectrum under 792nm excitation were measured.The intensity parameters(Ωt,t=2,4,6),oscillator strength(fcal),transition probabilities(A),branching ratios(β) and radiation lifetimes(τrad) of Er3+ ions in the LiYF4 were estimated by using the Judd-Ofelt theory.The near-and mid-infrared fluorescence properties of the sample were discussed.The results indicate that near infrared fluorescence at 1.5μm corresponding to the Er3+:4I13/2→4I15/2 transition is observed under 980nm excitation while mid-infrared fluorescence at 3.0μm corre-sponding to the Er3+:4I11/2→4I13/2 transition is detected under 792 nm excitation.The reason that caused the weakening of fluorescence at 3.0μm is analyzed.