Evidence of self-frequency doubling from two inequivalent Nd3+ centers in the La2CaB10O19:Nd3+ bifunctional crystal

Nd x La 2 − x Ca B 10 O 19 crystals with different Nd3+ concentrations were grown by the high-temperature flux method. Room-temperature spectroscopy, i.e., absorption, emission, and lifetime measurements, was used to obtain the signatures of two inequivalent Nd3+ centers in the crystal host. They are attributed to Nd3+ substitution of both La3+ and Ca2+ sites. Nonradiative energy losses were estimated with the help of the Judd-Ofelt analysis. Self-frequency doubling of the F3∕24→I11∕24 Nd3+ laser channel with 5% efficiency was demonstrated in the XZ principal plane. It is clearly shown that self-frequency doubling can occur from two inequivalent luminescent centers.