Optical spectroscopy of ACr3+- doped ( Gd, Ca) 3( Ga, Mg, Zr) 2Ga3O12 garnet

Abstract

In a gadolinium gallium garnet GGG crystal substituted by different cations (Ca 2+, Mg 2+, Zr 4+) we have studied the optical properties of Cr 3+-doping ions and compared them with those of Cr 3+-doped Gd 3(Ga, Sc) 2Ga 3O 12 (GSGG). At room temperature the 4T 2→ 4A 2 band is observed with a maximum at 7500 Å. At 4.4 K the 2E → 4A 2 line and the 4T 2 → 4A 2 band are superposed. The important inhomogeneous broadening of the line and non-exponential fluorescence decays as well as excitation and FLN spectra show that the Cr 3+ ions are located in multisites of different intermediate crystal field strengths.