Optical emission properties of Nd3+ in NaBi(WO4)2 single crystal

Abstract

Room temperature optical absorption measurements of Nd3+ in NaBi(WO4)2 single crystals grown by the Czochralski method have been used to calculate the following Judd-Ofelt intensity parameters Ω2 = 30.9 × 10−20, cm2, Ω4 = 12.0 × 10-20 cm2 and Ω6 = 9.3 × 10−20 cm2. Using these parameters the emission properties of Nd3+ in this host have been estimated with particular attention to the 4F3/2 energy level responsible for stimulated emission channels. The experimental branching ratios of this level are obtained from photoluminescence and agree with those calculated using the above Ωk parameters. The 4F3/2 emission has neligible non-radiative intrinsic losses and the 10 K lifetime at low Nd concentration, 0.9 × 1018 cm−3, is τexp = 143 μs. Even at 300 K and for a much higher Nd concentration, 4.0 × 1019 cm−3, non-radiative losses are moderate, giving a quantum efficiency n ≊ 0.85. The 4F3/2 emissions show a stronly polarized character. The largest emission cross-section occurs at λ = 1060.9nm for the 4F3/2 → 4I11/7 laser channel with a π-polarized character, σEMI = 16 × 10−20 cm2.