SELF-DIFFRACTION FROM FREE-SURFACE RELIEF GRATINGS IN A PHOTOREFRACTIVE BI12TIO20 CRYSTAL

Experimental results on self-diffraction of periodically phase-modulat ed laser beams from a relief grating formed on a free surface of a cub ic photorefractive Bi12TiO20 crystal due to the piezoelectric effect a re reported. Periodic intensity modulations of the reflected beams up to 10(-2) due to energy exchange at this unshifted phase grating are m easured, The modulation depends linearly on the fringe spacing and on the amplitude of an externally applied electric de field. The observed self-diffraction process is independent of the light polarization. (C ) 1998 American Institute of Physics.