Applied Nanophotonics, Liquid Crystals and Biomedical Optics

Short pitch deformable helix ferroelectric liquid crystals are shown to become optically isotropic at certain critical tilt angle with an average dielectric constant (ε ₁+ε ₂+ε ₃)/ 3. For uniaxial medium, this angle equals θ _d = cos ^-1(1/√3), and it depends weakly on the local biaxial anisotropy. The degeneracy is removed upon the application of a small electric field and the medium becomes optically biaxial. A high contrast fast electrooptic modulation and display devices can be built using such materials even when aligned in a multi-domain. For tilt angles very near the degeneracy angle, ultrasensitivity of the eigenaxes rotation to the applied field is found.