Judd–Ofelt analysis and optically stimulated two-photon absorption of Yb3+-doped NdAl3(BO3)4 single crystals

NdAl3(BO3)4 single crystals with different concentrations of Yb3+ were grown using the top seeded solution growth method. The absorption spectra of the grown samples were recorded at room temperature and analyzed using the standard Judd–Ofelt theory. Influence of Yb3+ concentration on the Nd3+ absorption properties was studied. Variation of the Nd3+ oscillator strengths with changing Yb3+ concentration suggests significant role of the Yb–Nd energy transfer in the formation of the absorption spectra. Following the absorption spectra we illuminated the investigated crystals at 532 nm absorption line to observe the changes of the two-photon absorption (TPA). We observed substantial increase of the TPA with the increased power of the illuminating laser which was proportional to the Yb content.