Ricerc@Sapienza

Dynamic diffraction gratings that are hidden in the field-off state are fabricated utilizing a room-temperature photocurable liquid crystal (LC) monomer and nematic LC (NLC) using holographic photopolymerization techniques. These holographic LC polymer-dispersed LCs (HLCPDLCs) are hidden because of the refractive index matching between the LC polymer and the NLC regions in the as-formed state (no E-field applied).

Diffractive waveplates (DWs) are highly efficient optical components realized by means of a polarization holography setup that makes use of UV/blue laser sources. It is more convenient to perform the holographic recording process with green lasers (e.g., continuous wave operating at 532 nm) because they offer compactness, efficiency, and high power. Unfortunately, the photo-alignment materials used forDWfabrication exhibit limited sensitivity at 532 nm.

Low molar mass liquid crystals (LCs) are typically not soluble in polymer systems to any great degree. When the two different materials are mixed, this leads to two-phase systems whose morphology depends on a variety of factors including, primarily, the concentration. The resulting two-phase structures can have inclusions with nanometer through macroscopic dimensions. Although there are a large number of variants, these structures are generically called 'polymer dispersed liquid crystals' (PDLCs) when the resulting morphologies lead to systems that scatter light.