Advances in photochromic computer-generated holograms

Photochromic materials belonging to the class of diarylethenes are presented as active materials for the manufacturing of rewritable Computer Generated Holograms (CGHs). Thanks to the modulation of both transparency and refractive index, it is possible to produce amplitude and phase holograms. Regarding the photochromic materials, different properties must be optimized in order to obtain efficient holograms and they are here discussed. As for the writing step, it is possible to use a direct laser writing approach or a mask projection system and both strategies are discussed. Examples of photochromic CGHs (phase and amplitude) are reported.