Growth and Spectral Properties of Er3+;LiYF4 Single Crystal

Er3+: LiYF4 single crystal was grown by the Bridgman method under non―vacuum atmosphere. The single crystal was in size of 9mm×68mm with 1mol% concentration of Er3+ ions. Optical properties of the single crystal including 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 (?t, t=2,4,6), oscillator strength(fcal), transition probabilities (A), branching ratios (B) and radiation lifetimes (trad) 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 corresponding 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.