Temperature dependence of two beam coupling, light-induced erasure decay and dark decay in As-grown and reduced BaTiO₃:Rh

Two beam coupling, light-induced erasure decay and dark decay are investigated in as-grown and reduced BaTiO₃:Rh as a function of temperature. The photorefractive sensitivity increases with temperature, mainly due to the increase of the speed. As deduced from the dark decay measurement, the shallow trap effect decreases while the dark conductivity increases with increasing temperature. These two factors determine how the two beam coupling gain depends on intensity and the intensity dependence power coefficient with response time varies as temperature increases. For the as-grown sample, the photorefractive properties are controlled by the competition between deep and shallow levels when the temperature is below 60°C. Above 60°C, large dark conductivity plays a dominant role. For the sample reduced at an atmosphere of 10^-10 atm oxygen partial pressure, the photorefractive properties are controlled by the competition between deep and shallow traps from room temperature to 100°C. For the sample reduced at an atmosphere of 10^-14 atm oxygen partial pressure, the photorefractive properties are mainly dependent on the dark conductivity though it has a high photoconductivity.