Near-infrared holographic photorefractive recording under applied electric field in undoped Bi$_{12}$TiO$_{20}$ sillenite crystal

Abstract

Direct holographic recording in undoped Bi$_{12}$TiO$_{20}$ crystal at 1064 nm is investigated aiming the characterization of diffraction efficiency under action of applied dc electric field ($E_0$). An enhancement of 12-fold in the diffraction efficiency was revealed when $E_0$ increased from 0.0 to 4.2 kV/cm. The theoretical dependence of the diffraction efficiency upon $E_0$ was investigated using the standard model for photorefractivity and the results showed a good experimental data fitting, allowing the computation of the effective trap concentration $(N_D$$)_{eff}$ $\approx$ $5.3\times 10^{15}$ cm$^{-3}$ which is responsible by the recording mechanism into the BTO crystal sample. The type of charge carrier involved in the recording mechanism in the nearinfrared region is also discussed.