Abstract

Er³⁺ ion, due to its energy level structure, is a very attractive activator for several laser applications. The main transitions are the ⁴S_3/2→⁴I_15/2 around 550 nm, the ⁴I_11/2→⁴I_13/2 around 3 μm and the ⁴I_13/2→⁴I_15/2 around 1.5 μm. One of the limiting factor in the use of Er³⁺ as active ion for the development of efficient 1.5 μm laser sources is the up-conversion processes between Er ions (⁴I_13/2, ⁴I_13/2)→(⁴I_15/2, ⁴I_9/2), that depopulates the ⁴I_13/2 level. To improve the efficient of Er³⁺ emission at 1.5 μm it is very important, to enhance the population inversion between the ⁴I_13/2 and the ⁴I_15/2 levels. A possible solution consists in the introduction of another rare earth ion that increases the population of Er³⁺ upper laser level through energy transfer mechanisms. For this reason we studied the emission properties of NaLa(WO₄)₂ crystals (NLW) in case of Er-Ce co-doping

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