Large improvements are reported in the sensitivity of optically addressed multiple quantum well spatial light modulators. In prior work with these materials the quantum well region has been made semi‐insulating. It is shown that this is unnecessary and in fact detrimental to performance. By placing layers containing high trap concentrations at the ends of the structure and leaving the active quantum well layers intrinsic the speed of the device at a given illumination is improved by more than four times, diffraction efficiency is enhanced and spatial resolution is almost the same. ©1995 American Institute of Physics.