Kinetics of the photorefractive response of bismuth silicon oxide

The kinetics of production and dark decay of index gratings in Bismuth Sili con Oxide was investigated as a function of write-beam intensity at 300 K a nd of temperature over the 20-300 K temperature range. At 300 K and an inte nsity of about 200 mW/cm(2) the gratings show a fast leading-edge peak whic h drops to a steady saturated value. At lower intensities the peak slows an d broaden, but the grating strength at saturation remains the same. As the temperature is lowered the gratings grow more slowly, and the peak disappea rs at about 200 K. The slowing and disappearance of the peak are probably r elated to the large decrease in electron mobility in this temperature range . Below 225 K the grating strength at the end of the 500 ms write time grow s significantly and reaches a maximum in the 125-150 K temperature region. The dark decays disappear quickly for temperatures down to about 180 K. At lower temperatures the decays become much slower and become persistent belo w 60 K. The largest change appears between 150 and 123 K. A persistent grat ing was written at 20 K, and its strength was measured as the sample warmed . The persistent grating annealed out between 110 and 150 K. The slowing of the dark decays and the anneal of the persistent grating correlate with th e reported recovery of Fe3+. (C) 2001 American Institute of Physics.