We study both experimentally and theoretically modulation of light in a planar aligned deformedhelix ferroelectric liquid crystal (DHFLC) cell with subwavelength helix pitch, which is also known as a short-pitch DHFLC. In our experiments, azimuthal angle of the in-plane optical axis and electrically controlled parts of the principal in-plane refractive indices were measured as a function of voltage applied across the cell. Theoretical results giving the effective optical tensor of a shortpitch DHFLC expressed in terms of the smectic tilt angle and the refractive indices of FLC are used to fit the experimental data. Optical anisotropy of the FLC material is found to be weakly biaxial. For both the transmissive and reflective modes, the results of fitting are applied to model phase and amplitude modulation of light in the DHFLC cell. We demonstrate that, if the thickness of the DHFLC layer is about 50 µm, the detrimental effect of field-induced rotation of the in-plane optical axes on the characteristics of an axicon designed using the DHFLC spatial light modulator in the reflective mode is negligible.

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The objective of this work is to assess characteristics and possible applications of an adjustable focusing device based on two crossed substrates for modal cylindrical lenses. The theoretical model of the device is presented and relations for control potentials are obtained for the case of a quasi-cylindrical lens. An experimental study of the device properties is carried out. An experiment is performed to focus light into a line segment with controllable orientation.

A solution to a general problem for 4-channel liquid crystal (LC) modulator (LC focusing device) of the formation of specified-equipotential-line voltage distribution and on its movement along the aperture is presented. The modulator’s capabilities for the formation and control of light fields in the form of circles, line segments and ellipses of an arbitrary orientation are demonstrated numerically and experimentally.