Light-induced and holographic properties of ruthenium and manganese co-doped Bi₄Ge₃O₁₂ crystals

The effect of Ru + Mn co-doping on the light-induced properties of Bi ₄Ge₃O₁₂ (BGO) crystals is studied and compared with single Ru-and Mn-doped crystals. Optical absorption spectra of Ru + Mn co-doped crystal demonstrates a photosensitivity shift to the visible spectral range. In addition, a strong photochromic effect, being fully reversible by thermal annealing is observed. It is verified by photoluminescence emission that charge traps could be manipulated under ultraviolet (UV) excitation, as the photoluminescence intensity decreases revealing the existence of the state filling effect. Ru + Mn doping leads to a faster response time during holographic recording at 633nm and a prolonged read-out process, especially after a preliminary exposure to UV light. The ability to modify the defect structure and corresponding absorption bands suggests the future potential for optical fixing using a two-step sensitization method.