Dye-doped Liquid Crystals (LCS) are very attractive materials for many applications (Optically Addressed Spatial Light Modulators, dynamic holography, alloptical switching) because of their high sensitivity to optical fields, possibility of use in transmission and low cost. The complexity of the physical effects (surface mediated and bulk) which take place in a doped cell when it is illuminated [1-4], hampers the simple engineering of devices. A good understanding of these effects is a primary goal of this research. A comparison of materials based on temporal and spatial resolution and efficiency is presented. Photorefractive-like effects and various underlying mechanisms are considered.