A new photopolymerizable material allows single-step, fast recording of
volume holograms with properties that can be electrically controlled.
Polymer-dispersed liquid crystals (PDLCs) in accordance with the
invention preferably comprise a homogeneous mixture of a nematic liquid
crystal and a multifunctional pentaacrylate monomer, in combination with
photoinitiator, coinitiator and cross-linking agent. Optionally, a
surfactant such as octanoic acid may also be added. The PDLC material is
exposed to coherent light to produce an interference pattern inside the
material. Photopolymerization of the new PDLC material produces a
hologram of clearly separated liquid crystal domains and cured polymer
domains. Volume transmission gratings made with the new PDLC material can
be electrically switched between nearly 100% diffraction efficiency and
nearly 0% diffraction efficiency. By increasing the frequency of the
switching voltage, switching voltages in the range of 50 Vrms can be
achieved.