Spectroscopic properties and microchip laser performance of Yb:LaCa4O(BO3)3 crystal

Abstract

In this work, the polarized absorption and emission spectra of the Yb:LaCa4O(BO3)3 (Yb:LaCOB) crystal were studied, and the microchip laser performance was investigated with 1.0 mm thick crystals cut along its three principal optical axes. The strongest absorption is found to occur at 977.2 nm for E//X, with the cross-section amounting to 2.21 × 10−20 cm2, the largest for all of the Yb-doped oxyborates developed so far; whereas the maximum cross-section of the main emission band, 0.30 × 10−20 cm2 for E//Z, proves to be the smallest among all the Yb-doped oxyborates. The X-cut microchip crystal laser could be operated simultaneously in the main emission band and in the long-wavelength sideband, producing an output power of 2.15 W with optical conversion efficiency of 48.1 %. While operated in the emission sideband, the Z-cut microchip laser could generate 2.14 W of output power at 1068.6–1077.8 nm with an optical conversion efficiency of 45.1 %. Output power of 2-W level could also be produced from the X-cut microchip laser operating at 1028.1–1033.6 nm, or from the Z-cut microchip laser operating at 1042.7–1050.7 nm, with optical conversion efficiencies higher than 40 %.