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Growth and spectroscopic investigations of the 1.5 at.% Er:GSGG laser crystal

The 1.5 at.% Er3+ doped gadolinium scandium gallium garnet (GSGG) laser crystal with high optical quality was successfully grown by the Czochralski method. The structural parameters were obtained by x-ray Rietveld refinement. A high crystalline quality of Er:GSGG was determined by x-ray rocking curve. The spectroscopic parameters of Er3+ ion were calculated and analyzed using the Judd–Ofelt theory. Furthermore, the stimulated-emission cross-section spectra were investigated for the 4I13/2  →  4I15/2 transitions at 1.5–1.6 µm, which indicates the great potential of Er:GSGG for multi-wavelength emission at 1.5–1.6 µm. The larger emission cross-section and long fluorescence lifetimes around 0.55 and 0.67 µm mean that the 1.5 at.% Er:GSGG crystal is beneficial for green and red laser generation. Meanwhile, the intensity of the emission spectra was compared between the 1.5 at.% and 2.0 at.% Er-doped GSGG. The roles of cross-upconversion, cross-relaxation and the excited-state absorption process were discussed in the 1.5 at.% Er:GSGG crystal for generating visible and 1.5–1.6 µm lasers.