Laser dynamics and upconversion processes in Nd3+-doped yttrofluorite crystals

The study of upconversion processes producing ultraviolet and visible emissions in yttrofluorite mixed crystals with 15 wt% of YF3 and 1, 4, 8, and 16 wt% of NdF3 is presented. Site-selective excitation of Nd-doped yttrofluorite crystals by using spectrally narrow pump pulses have shown it is possible to lase these materials in single line at 1054 nm or at 1063 nm independently, or simultaneously in both lines depending on the Nd3+ concentration and excitation wavelength. The upconversion measurements were performed under lasing and nonlasing conditions. The dynamics of the upconverted emission shows that both energy transfer upconversion and excited state absorption of the laser emission and pump radiation occur, being the process strongly dependent on the Nd3+ concentration.