Orientational Kerr effect and phase modulation of light in deformed-helix ferroelectric liquid crystals with subwavelength pitch

Abstract

We study both theoretically and experimentally the electro-optical properties of vertically aligned deformed helix ferroelectric liquid crystals (VADHFLC) with subwavelength pitch that are governed by the electrically induced optical biaxiality of the smectic helical structure. The key theoretical result is that the principal refractive indices of homogenized VADHFLC cells exhibit the quadratic nonlinearity and such behavior might be interpreted as an orientational Kerr effect caused by the electric-field-induced orientational distortions of the FLC helix. In our experiments, it has been observed that, for sufficiently weak electric fields, the magnitude of biaxiality is proportional to the square of electric field in good agreement with our theoretical results for the effective dielectric tensor of VADHFLCs. Under certain conditions, the 2π phase modulation of light, which is caused by one of the induced refractive indices, is observed without changes in ellipticity of incident light.

Simulation Study on Polarization-Independent Microlens Arrays Utilizing Blue Phase Liquid Crystals with Spatially-Distributed Kerr Constants

“…In 2010, we proposed a polarization independent polymer stabilized blue phase liquid crystal (PSBP-LC) microlens arrays based on the electric-field-induced Kerr effect, the field-induced birefringence is proportional to the electric field squared [11]. The Kerr effect exists in many LC materials, such as polymer stabilized isotropic phase liquid crystals, nematic liquid crystals, blue phase liquid crystals, and even ferroelectric liquid crystals [12][13][14]. In this paper, we proposed polarization independent LC microlens arrays based on controlling the distribution of the Kerr constants of blue phase LC (BPLC).…”

Electro-Optical Modulation in Planar Aligned Ferroelectric Liquid Crystals with Subwavelength Helix Pitch

“…Pure phase modulation of light, when the phase shift can be smoothly tuned from zero to 2π in electric field E at frequency around 1 kHz or more and without any essential change of the light ellipticity, is required for development of such modern photonic devices. These requirements can be satisfied using vertically aligned deformed helix ferroelectric liquid crystal (VADHFLC) with sub-wavelength helix pitch [10,11], under conditions illustrated in Figure 1 a b c Fig. 1.…”

Optics of short-pitch deformed-helix ferroelectric liquid crystals: Symmetries, exceptional points, and polarization-resolved angular patterns

“…Biaxial anisotropy and rotation of the in-plane optical axes produced by the electric field can be interpreted as the orientational Kerr effect [8,9].…”