Dielectric anisotropy, and diffraction efficiency properties of a doped nematic liquid crystal

The dielectric anisotropy and diffraction efficiency properties of E7 liquid crystal and SPCI-C7 doped liquid crystal composite have been investigated. The dielectric constant components (ɛ∥ and ɛ⊥) in the nematic phase of E7 were measured as a function of frequency. The liquid crystals exhibited dielectrically-controlled positive dielectric anisotropy (p-type Δɛ) with transition to negative dielectric anisotropy (n-type Δɛ). SPCI-C7 doping lowered dielectric anisotropy and increased the diffraction efficiency of E7. The refractive index modulation values of E7 and E7/SPCI-C7 were Δn = 3.9 × 10−3 and Δn = 6.95 × 10−3, respectively, and this parameter was increased by doping.