Diffraction efficiency enhancement of holographic gratings in Bi12Ti0.76V0.24O20 crystals after recording

Abstract

An enhancement of the diffraction efficiency of holographic gratings in Bi(12)Ti(0.76)V(0.24)0(20) crystals by a factor of almost 40 is obtained after recording by application of an external de electric field and illumination with a spatially homogeneous light beam. The enhancement increases with increasing applied field, larger spatial frequency, and longer writing time of the holographic grating, and with intensity of the homogeneous illumination. A theoretical description of the enhancement effect is proposed, assuming a modulated photoconductivity, which is generated by a strongly modulated concentration of photorefractive traps or donors. (C) 1996 Optical Society of America.