Efficient near-infrared laser emission and nonlinear optical properties of a newly developed Yb:LYSB laser crystal

Abstract

Herein, we report on the growth and characterization of La0.78Y0.32Yb0.04Sc2.86(BO3)4 (Yb:LYSB) crystal as bifunctional laser and nonlinear optical (NLO) medium. High quality Yb:LYSB crystal with non-congruent melting has been grown by the Czochralski technique. Structural, linear and NLO properties, and near-infrared (NIR) laser emission performances of the grown crystal are presented. The absorption cross-section at 980 nm for σ-polarization was evaluated to be 0.6 × 10−20 cm2, and emission cross-section around 1080 nm in π-polarization and σ-polarization amounted to 3.6 × 10−21 cm2 and 1.33 × 10−21 cm2, respectively. The spectroscopic investigations revealed the existence of two different Yb3+ centers in the LYSB crystal matrix. Efficient laser emission at 1028 nm was obtained with a c-cut 4 at.% Yb:LYSB uncoated sample with a thickness of 3.5 mm. Employing the pump at 971.5 nm with a fiber-coupled diode laser, the Yb:LYSB medium yielded laser pulses with 1.5 mJ energy at 4.25 mJ energy of the absorbed pump pulse, corresponding to an overall optical-to-optical efficiency of 0.35. The laser operated with a high slope efficiency of 0.57. The refractive indexes were measured and the NLO properties of Yb:LYSB crystal for second harmonic generation of 1028 nm laser radiation were determined. The results of this work indicate Yb:LYSB as a promising crystal to design new laser sources in the NIR and green (∼514 nm) spectral ranges based on direct laser emission and self-frequency doubling processes, respectively.