Crystal growth, first-principles calculations, and enhanced 1.5–1.7 μm fluorescence emission from the Er, Ce: CaGdAlO4 laser crystal

Abstract

Near-infrared (NIR) laser radiation based on Er³⁺-doped crystals has attracted considerable attention owing to its important applications in medical imaging, spectroscopy, remote sensing, and space communication. Co-doped Ce³⁺ ions can effectively enhance the fluorescence emission intensity of the 1.5–1.7 μm band of Er³⁺ ions, which is expected to achieve a lower threshold and higher efficiency of the NIR band laser output. However, the relationship between the structure and luminescence of laser crystals has not been well established yet. In this study, Er, Ce: CaGdAlO₄ (Er, Ce: CGA) laser crystals were grown and studied for the first time. The mechanism of the structure–luminescence relationship was investigated using first principles calculations based on density-functional theory (DFT). It was observed that the fluorescence emission intensity and the full width at half maximum depended on the atomic spacing of Er³⁺–Ce³⁺ ion pairs in the Er, Ce: CGA crystal. Furthermore, based on the optimal Ce³⁺ doping concentration obtained from the structure–luminescence relationship, a 1.5–1.7 μm broadband and enhanced emission was acquired for the first time. This study provides a theoretical and experimental basis for obtaining a new type of laser gain medium that is promising for all-solid-state lasers in the 1.5–1.7 μm region.