Systematically revealing color centers origin and properties optimisation after elimination in Lu2O3 single crystal

Rare-earth sesquioxides crystals, especially Lu2O3 crystals, have become a hot topic in solid-state laser research due to its high thermal conductivity, low phonon energy and high laser damage threshold. However, available bulk Lu2O3 crystals grown from the melt generally suffer from color centers, limiting the further applications. Here, the origins of the color center were systematically investigated for the first time through three-stage annealing experiments, absorption spectra, density functional theory and X-ray photoelectron spectroscopy, revealing that oxygen vacancies are the main cause for color centers. On this basis, the influence of eliminating color center by annealing on the crystal properties were also well demonstrated. The crystallinity as well as the optical properties of Lu2O3 crystals were significantly enhanced after annealing, providing a promising candidate for high-power solid-state lasers.