Crystal growth, spectroscopic characterization, tunability, and ultrafast pulse laser properties of Yb:LaF₃ crystal

A 1 at.% doped Yb:LaF₃ crystal was grown by the Bridgman method. The Raman, absorption, and fluorescence properties at room temperature were investigated systematically. The phonon energy, absorption cross-section, and emission cross-section of the Yb:LaF₃ crystal were 362 cm^-1, 0.35 × 10^-20 cm², and 0.55 × 10^-20 cm², respectively. The laser characteristics of Yb:LaF₃ crystals were demonstrated, including continuously tunable laser and passively mode-locked laser. Using a birefringent filter, the continuously tunable laser was obtained with a tunable range from 1011 nm to 1031 nm. An ultrashort pulse laser of 56 ps was achieved using a semiconductor saturable absorber mirror as a saturable absorber, resulting in a repetition rate of 90.10 MHz and a maximum average output power of 132 mW. The mode-locked laser corresponded to a pulse energy of 1.47 nJ and a peak power of 28.76 W. These results, underpinned by the crystal's advantageous properties such as an intrinsically broad emission bandwidth (52 nm), indicate that the Yb:LaF₃ crystal is a promising material for developing tunable and ultrafast pulse lasers in the near-infrared regime.