Experimental investigation and crystal-field modeling of Er3+ energy levels in GSGG crystal

• The efficient diode-end-pumped laser crystal Er:GSGG has been grown successfully.
• The absorption spectra of Er:GSGG have been measured in range of 350–1700 nm.
• The fitting result is very well for the root mean square deviation is 9.86 cm−1.
• The 124 levels of Er:GSGG have been assigned from the crystal-field calculations.

The Er3+-doped Gd3Sc2Ga3O12 (Er3+:GSGG) single crystal, a excellent medium of the mid-infrared and anti-radiation solid state laser pumped by laser diode, was grown by Czochralski method successfully. The absorption spectra were measured and analyzed in a wider spectral wavelength range of 350–1700 nm at different temperatures of 7.6, 77, 200 and 300 K. The free-ions and crystal-field parameters were fitted to the experimental energy levels with the root mean square deviation of 9.86 cm−1. According to the crystal-field calculations, 124 degenerate energy levels of Er3+ in GSGG host crystals were assigned. The fitting results of free-ions and crystal-field parameters were compared with those already reported of Er3+:YSGG. The results indicated that the free-ions parameters for Er3+ in GSGG host are similar to those in YSGG host crystals, and the crystal-field interaction of GSGG is weaker than that of YSGG, which may result in the better laser characterization of Er3+:GSGG crystal.