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The mesophase properties of nematic liquid crystals render them ideal for controlling and studying topological defects. The planar soliton, a π‐wall in the form of a string with a constant thickness shown in a nematic, is a topological defect lacking singularity. Herein, a thermal laser tweezer is introduced to trap the disclination at the isotropic–nematic interface induced by the thermal effect and to move the trapped disclination under the low anchoring condition, which enables to generate solitons as if they were drawn and to control them actively. The soliton, which is created or annihilated in accordance with topological charge conservation, exhibits cosmic string intercommutation. Thus, the dynamics of cosmic strings can be implemented by using solitons in a nematic. To demonstrate potential applications of the solitons, microsized cargo delivery and polarization diffraction gratings are presented, which could be used in lab‐on‐a‐chip and implemented in various photonic applications, respectively, and prove the applicability of a topological defect through complete control. [ABSTRACT FROM AUTHOR]

In this work, we present a method to generate vector beams with a 4f polarization Fourier filtering system that combines a spatial light modulator (SLM) at the input plane and a polarization diffraction grating (PDG) at the output plane. In the Fourier plane, two quarter-wave plates are employed to transform the +1 and −1 diffraction orders onto circular right (RCP) and left (LCP) polarizations, respectively. The PDG at the output plane recombines the two beams producing the colinear superposition of RCP and LCP beams. The application of a random encoding technique to multiplex diffractive elements on the SLM allows the independent encoding of different patterns on the final beam, thus arbitrary vector beams can be generated at the output. Experimental results are included that demonstrate the capability for this approach to encode a variety of polarization vector beams with different topological charges. [ABSTRACT FROM AUTHOR]

Technique for real-time spectropolarimetry is developed. An embedded system for circular dichroism registration is designed based on National Instruments single board reconfigurable I/O platform for ultraviolet and visible spectroscopic needs. The basic functional unit of the proposed device is liquid crystal polarization diffraction grating. In order to expand the dynamic range the control of data accumulation time is provided. Two NMOS sensor linear arrays provide an excellent linearity of response. [ABSTRACT FROM AUTHOR]

In this paper, we present a study of the photoinduced processes in films of N-benzylideneaniline incorporated in a polymethylmethacrylate (PMMA) matrix both by spectrophotometric and holographic methods. Photodichroism of the order of ΔD = 0.15 is induced in the films by polarized UV light at room temperature. We are also able to record stable holographic gratings in these materials for the first time to the best of our knowledge. [ABSTRACT FROM AUTHOR]