[en] Persistent photoinduced changes of optical absorption have been found in garnet Ca₃Ga₂Ge₃O₁₂ doped with manganese. Irradiation by a He--Ne laser of 633 nm wavelength results in a noticeable increase in the absorption coefficient of the crystal. The photoinduced changes are observed up to room temperature as distinct from concentrated manganese garnets in which the photoinduced absorption vanishes at much lower temperatures. The wide temperature range of the existence of the photoinduced effect together with a high transparency of the crystal makes it a promising material for optical recording. Copyright 2001 American Institute of Physics

[en] Optical absorption spectra of YbAl₃(BO₃)₄, TmAl₃(BO₃)₄ and TbFe₃(BO₃)₄ trigonal crystals have been studied in temperature range 2–300 K. Temperature behavior of absorption lines parameters has shown, that during some f-f transitions the local environment of rare earth ions undergo distortions, which are absent in the ground state.

[en] Long-lived photoinduced absorption and dichroism in the Ca₃Ga_2-xMn_xGe₃O₁₂ garnets with x < 0.06 were examined versus temperature and pumping intensity. Unusual features of the kinetics of photoinduced phenomena are indicative of the underlying electronic processes. The comparison with the case of Ca₃Mn₂Ge₃O₁₂, explored earlier by the authors, permits one to finally establish the main common mechanisms of photoinduced absorption and dichroism caused by random electric fields of photoproduced charges (hole polarons). The rate of their diffusion and relaxation through recombination is strongly influenced by the same fields, whose large statistical straggling is responsible for a broad continuous set of relaxation components (observed in the relaxation time range from 1 to about 1000 min). For Ca₃Ga_2-xMn_xGe₃O₁₂, the time and temperature dependences of photoinduced absorption and dichroism bear a strong imprint of structure imperfection increasing with x