Spectroscopic analysis of Er3+ transition in Mg/Er-codoped LiNbO3 crystal

We present a Judd-Ofelt spectroscopic analysis on the Mg/Er-codoped congruent lithium niobate (LiNbO3) crystals. The Judd-Ofelt model is applied to the room temperature unpolarized absorption intensities of Er3+ ions on eleven transition bands to determine their intensity parameters: Ω2=2.36×10−20 cm2, Ω4=0.76×10−20 cm2, Ω6=0.30×10−20 cm2 in Er:LiNbO3 crystal heavily codoped with MgO. The radiative lifetime of 2H9/2 becomes longer when MgO is added into Er:LiNbO3 crystal. The experimental lifetimes are obtained using microsecond time-resolved spectra at 400 nm femtosecond pulse excitation to predict radiative quantum efficiency. Combining higher radiative quantum efficiency with longer radiative lifetime, we conclude that Mg/Er-codoped LiNbO3 crystals are more suitable than Er: LiNbO3 ones in laser materials.