Spectral properties and laser performance of Ho:CNGG crystals grown by the micro-pulling-down method

Ho3+-doped calcium niobium gallium garnet (Ho:CNGG) single crystals have been successfully grown by the micro-pulling-down (µ-PD) method. The crystal structure, spectral properties, and laser performance of Ho:CNGG crystals were investigated. The doped Ho3+ ions showed a broad absorption and fluorescence bands due to the random distribution of Nb5+, Ga3+ and cationic vacancies in the host lattices. Moreover, 1.0 at.% Ho:CNGG single crystal was end-pumped by using a diode-pumped Tm:YAP laser with central wavelength of 1937nm. The maximum output power of 1.4 W with a slope efficiency of 18.7% at 2080nm was obtained preliminarily.