We consider a nematic liquid crystal constrained by two coaxial cylinders under the action of low-frequency axial or radial electric fields. Assuming an initially hybrid configuration, we find the equilibrium texture of the nematic subjected to weak anchoring boundary conditions on both cylindrical surfaces. We analyze the distinct textures of the nematic as a function of the strength of the interaction of the nematic with the sidewalls, the radii ratio of the cylinders, and the applied electric field. Also, for each radii ratio and strength of the nematic-surface interaction, we determine the critical field for which a complete alignment of the nematic liquid crystal occurs.

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We considered a cholesteric slab whose axis is normal to their borders, when a uniform electric field is perpendicularly applied to the helix axis. We found the solution of the boundary value problem for the reflection and transmission of normally incident waves due to the slab. We showed that a left-circularly polarized thin reflection band is immersed in a wider right-circularly polarized band reflection, when the cholesteric is subjected to low amplitude fields. For larger field values, both reflection bands redshift simultaneously as the field increases. A device based on this phenomenon can be used as a electrically tunable universal filter.

We consider a model for a one-dimensional photonic crystal formed by a succession of Kerr-type equidistant spaceless interfaces immersed in a linear medium. We calculate the band structure and reflectance of this structure as a function of the incident wave intensity, and find two main behaviors: the appearance of prohibited bands, and the separation and narrowing of these bands. A system with these features is obtained by alternating very thin slabs of a soft matter material with thicker solid films, which can be used to design a device to control light propagation for specific wavelength intervals and light intensities.