Photorefractive multiple quantum well (PRMQW) devices can achieve simultane
ously higher resolution and greater sensitivity by distributing several hig
hly trapping low temperature growth (LTG) layers at different depths in the
ir intrinsic region. This article extends a previously derived analytical m
odel of PRMQW devices to distributed photorefractive devices (DPDs) that co
nsist of a cascade of smaller MQW regions sandwiched between LTG layers. Th
is enables an understanding of how multiple trapping layers affect the reso
lution and sensitivity in these DPDs. In addition to an improvement in reso
lution, the model predicts an enhancement in diffraction efficiency at smal
l grating spacings as the number of subdevices increases for a fixed total
DPD length. This result is of significance in designing compact image proce
ssing systems that can operate at small grating periods but still be able t
o achieve a large signal-to-noise ratio for image processing and sensing ap
plications. (C) 2000 American Institute of Physics. [S0021-8979(00)00722-2]
.