Enhancement and control of switched phase-conjugate reflectivity in a BaTiO3 crystal

When a pulsed backward pump beam (pulse width∼1 sec) with a suitable time period (e.g., T=90 sec) is irradiated as a reading beam on a steady-state transmission grating in a BaTiO₃ crystal, with a degenerate four-wave mixing geometry, the switched value of the phase-conjugate reflectivity can be increased by some factors of magnitude over the initial value under a suitable condition. A maximum of the enhanced reflectivity can be controlled by adjusting the interacting beam powers. An increase in the diffraction efficiency is also found with the same read-out process, which plays a key role to this unusual enhancement of the phase-conjugate reflectivity as our knowledge.