Nondestructive readout of a photorefractive hologram by phase-conjugate copying in a one-crystal configuration

We propose a novel phase-conjugate copying method for nondestructive readout of a volatile photorefractive hologram. In the one-crystal configuration, two holographic memories and a mutually pumped phase conjugator (MPPC) are formed within a single photorefractive crystal, instead of using multiple crystals. Two memories share the same hologram and complement each other in refreshing the hologram. A MPPC suppresses fanning noise and automatically aligns the wavefront of the reference and readout beams. We found the optimum configuration to achieve nondestructive readout from calculations and geometric consideration. In the experiments with a BaTiO(3) crystal, a continuous readout of 20 times longer than the recording time was achieved.