Study of photoconductivity and holographic current in rare-earth-doped Y 3 Sc 2 Ga 3 O 12 laser crystals

The photoconductivity and holographic current have been studied in Er-, Tm-, and Ho-doped Y3Sc2Ga3O12 laser crystals under visible and infrared excitation. Kinetics and spectroscopic studies have shown that photoconductivity is linearly proportional to the concentration of excited 4f states. The holographic current was described with a model accounting for the energy transfer between the rare-earth and ligand electronic shells, ionization, recombination, and the diffusion and drift currents in the conduction band. The dependence of the holographic current on the modulation frequency, grating vector, etc. were used to determine the carriers’ diffusion length and the screening length in Er-doped crystals.