SELF-ENHANCEMENT OF DYNAMIC GRATINGS IN PHOTOGALVANIC CRYSTALS

We have developed a compact closed-form solution of the band transport model for high-contrast gratings in photogalvanic crystals. Our solut ion predicts the effect of the photoconductivity and the electric fiel d grating enhancement due to the photogalvanic effect. We predict a pr onounced dependence of the steady-state photogalvanic current on the c ontrast of the interference pattern and an increase of holographic sto rage time due to the enhancement of the photoconductivity grating cont rast. In the high contrast Limit and a large photogalvanic effect the refractive index grating will be shifted from the position of the inte nsity modulation pattern, contrary to the usually adopted model of uns hifted gratings. [S1050-2947(98)03610-5].