Some embodiments include memory cells which contain, in order; a first electrode material, a first metal oxide material, a second metal oxide material, and a second electrode material. The stents consist of a plurality of radially expandable cylindrical elements generally aligned on a common longitudinal stent axis and interconnected by one or more interconnecting members placed so that the stent is flexible in a longitudinal direction. An E-O modulator in the illumination path can modulate the polarization.