Hydrogen as origin of thermal fixing in LiNbO3: Fe

Abstract Protons are identified as the mobile ions, which neutralize the electronic space charge fields during thermal fixing of holograms in LiNbO3:Fe. The protons form OH− centers and can be observed via vibrational absorption bands. In crystals with reduced OH− content holograms cannot be fixed thermally. In crystals containing fixed patterns the OH− concentration shows a spatial variation corresponding to the electric charge distribution.