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Spectroscopic and photoluminescent studies of magnesium- and erbium-codoped lithium niobate crystal

A heavily magnesium (5.0 mol%) and erbium (2.0 mol%) codoped lithium niobate crystal has been grown using Czochralski method. The crystal is highly transparent and has strong resistance to photorefractive damage. Spectroscopic study showed that the crystal exhibits the typical f-f transitions of erbium ions. Photoluminescence at 1.54 micrometers was measured under excitations at 514 nm from an Ar+ laser and 980 nm from a GaAs laser diode. The temporal evolution of the 1.54 micrometers emission showed a single-exponential decay with a lifetime of approximately 5 ms. Upconversion property of the crystal under 980 nm excitation was also studied and the transient spectrum of the green emission at 548 nm also yields a single-exponential decay with a lifetime of approximately 35 microsecond(s) . The results have shown that clustering and pairing of Er ions could be effectively avoided by magnesium codoping.