Absorption Properties of Neodymium-Doped Laser Crystals for Low Quantum Defect Pumping

We report on the absorption coefficients of several popular Neodymium-doped laser crystals at wavelengths longer than 870 nm. In this study, high-resolution absorption spectra of Nd:YVO
4
, Nd:GdVO
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, Nd:YAG, Nd:YLF, and the composite Nd:YVO
4
/Nd:GdVO
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crystals were measured in the 870-920 nm range to identify suitable wavelengths for excitation. Such wavelengths correspond to the lowest quantum defects in these crystals. According to the obtained absorption spectra, the most appropriate pumping wavelengths of the individual Nd:YVO
4
and Nd:GdVO
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crystals are 914 and 912 nm, respectively. At the same time the composite Nd:YVO
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/Nd:GdVO
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crystal provides a broad absorption spectrum approximately between 910 and 916 nm. Moreover, the absorption spectra of Nd:YAG and Nd:YLF crystals reveal that laser diodes at 946 nm and 908 nm can be the best choice to excite these two widely used gain media.