Optimization of Optical Phase Profile in Beam Deflector with Advanced Simulation Method for High Diffraction Efficiency.

Controlling the phase of light with a high efficiency and precision is essential for applications in imaging, tunable devices, and optical systems. Spatial light modulators (SLMs) based on liquid crystals (LCs) have been regarded as one of the best choices for the generation of phase profiles for the steering of light. The upper glass substrate has an unpatterned electrode for a common electrode, while the lower glass substrate has one-dimensional micro-patterned electrodes for controlling the single pixel level by the applied voltages.

Liquid crystal microlenses based on binary surface alignment controlled by focused ion beam treatment.

We report the formation of high optical power microlenses in the near-surface region of the liquid crystal layer. Such microlenses, possessing a very small focal length at a rather large aperture A (/∼2), are able to focus the light into spots of a characteristic size comparable with the wavelength. Using numerical modeling, a specific patterning profile of a liquid crystal (LC) alignment surface by an ion beam is proposed to provide the aligning properties necessary for the formation of an array of microlenses with a focal length comparable to the LC cell thickness.

Liquid-Crystal Metasurfaces Self-Assembled on Focused Ion Beam Patterned Polymer Layers: Electro-Optical Control of Light Diffraction and Transmission.

Self-assembling of liquid-crystal metasurfaces on polymer layers patterned by a focused ion beam manifests itself in distinctly colored optical transmission, as light from certain spectral bands is efficiently diffracted by the periodic liquid crystal modulations. We explore the metasurface electro-optics by applying voltage across the liquid crystal to straighten its director distribution and reroute the diffracted light into the direct transmission. We show that the characteristic times of switching from the diffracting to the transmitting state can be decreased down to a millisecond by increasing the driving voltage up to 6-8 V, while the main part of the relaxation back into the periodically deformed diffracting state occurs within about a few milliseconds, i.

Precise local control of liquid crystal pretilt on polymer layers by focused ion beam nanopatterning.

The alignment of liquid crystals by surfaces is crucial for applications. It determines the director configuration in the bulk, its stability against defects and electro-optical switching scenarios. The conventional planar alignment of rubbed polymer layers can be locally flipped to vertical by irradiation with a focused ion beam on a scale of tens of nanometers.

Liquid crystal metasurfaces on micropatterned polymer substrates.

Formation of photonic liquid crystal metasurfaces on rubbed polyimide substrates patterned by focused ion beam is demonstrated. Modulation of the surface anchoring conditions with periods from 1 to 6 micrometers gives rise to periodic deformation of the nematic liquid crystal director field. The exact periodicity is confirmed by the light diffraction measurements.

Nematic liquid crystal alignment on subwavelength metal gratings.

We have studied the alignment of a nematic liquid crystal (LC) material on aluminum subwavelength nanogratings as a function of the period, , and the slit width to period ratio, . A method, based on Fourier analysis of the transmittance spectra of the LC grating system, has been applied. We show that the gratings provide stable planar alignment only for shorter periods and narrower slits ( < 400 nm, / < 2/3).

Study of the vertically aligned in-plane switching liquid crystal mode in microscale periodic electric fields.

The ongoing interest in fast liquid crystal (LC) modes stimulated by display technology and new applications has motivated us to study in detail the in-plane switching (IPS) vertically aligned (VA) mode. We have studied how the decrease of the period of the interdigitated electrodes (down to sub-micrometer scale) influences the switching speed, especially the LC relaxation to the initial homeotropic state. We have found that there are two types of the relaxation: a fast relaxation caused by the surface LC sub-layer deformed in the vicinity of the electrodes and the slower relaxation of the bulk LC.