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.