Angular dependences of transmission spectra of chiral liquid crystals

Umanskiĭ, B. A.; Simdyankin, I. V.

doi:10.1134/s1063774517030233

Cited by 4 publications

(7 citation statements)

References 14 publications

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“…The off‐band decrease in transmittance observed in these spectra is due to scattering losses, in part ascribable to an increase in the path length in the medium and to changes in the effective refractive index of the CLC layer with incidence angle. The appearance of the total reflection region for CLC‐1, where effectively both RCP and LCP light cannot propagate through the medium, is fully consistent with previous experimental observations and modeling of the light propagation through anisotropic helical structures …”

Section: Resultssupporting

confidence: 87%

“…It should also be noted that the shape of the reflection band is not symmetric at large incidence angles and the band is usually wider on the long wavelength side than on the short wavelength side of the total reflection region. This has previously been observed experimentally and obtained in numerical calculation by a 4 × 4 matrix method . The dynamical theory approach of Beliakov and Dmitrienko, however, predicts an approximately symmetric band, as discussed in ref.…”

Section: Resultssupporting

confidence: 63%

“…The optical layouts typically include large prisms, as was done in this study. In some literature cases, prisms actually constituted the substrates of the CLC device . Hemispherical elements have also been used .…”

Section: Discussionmentioning

confidence: 99%

“…The behavior was described theoretically by Belyakov and Dmitrienko . A detailed experimental analysis was carried out by Takezoe et al Subsequent investigations have focused on providing additional understanding of the optical properties of CLCs probed at oblique incidence …”

Section: Introductionmentioning

confidence: 99%

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Electrical Control of Unpolarized Reflectivity in Polymer‐Stabilized Cholesteric Liquid Crystals at Oblique Incidence

Tondiglia

Rumi

Idehenre

et al. 2018

Advanced Optical Materials

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The cholesteric liquid crystal phase at or near normal incidence selectively reflects circularly polarized light matching the handedness of the helicoidal superstructure. At large angles of incidence, both senses of circularly polarized light are reflected over a certain wavelength range. Stabilizing the cholesteric liquid crystal phase with low concentrations of polymer network that maintains structural chirality allows the pitch (and accordingly, the selective reflection) to be adjusted with an electric field. Here, the behavior of these polymer stabilized cholesteric liquid crystals is investigated at large angles of incidence, to determine how the total reflection evolves when the polymer network is deformed by an external DC field. Strong, unpolarized reflection is observed in polymer stabilized cholesteric liquid crystals at oblique angles over a wide range of field values. As the application of a DC electric field can adjust the position or bandwidth of the total reflection in polymer stabilized cholesteric liquid crystals, these reconfigurable devices could find potential end use in optical applications where polarization independent properties are needed, such as spectroscopy and polarimetry.

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Section: Resultssupporting

confidence: 87%

Section: Resultssupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Electrical Control of Unpolarized Reflectivity in Polymer‐Stabilized Cholesteric Liquid Crystals at Oblique Incidence

Tondiglia

Rumi

Idehenre

et al. 2018

Advanced Optical Materials

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show abstract

“…The unique feature seen in Figure is the transition from circularly polarized reflection (∼50% transmission) at angles near normal incidence to unpolarized reflection (>99% reflection) at high incidence angles. There have been several other theoretical and experimental explorations aimed at better understanding this angle-dependent spectral and polarization behavior. − At normal incidence, one of the two eigenmodes cannot propagate through the CLC medium and is reflected, while the other does not interact with the medium and is transmitted. At oblique incidence, both eigenmodes are diffracted by the medium to various extents.…”

Section: Introductionmentioning

confidence: 99%

A Different Perspective on Cholesteric Liquid Crystals Reveals Unique Color and Polarization Changes

Lee

Rumi

Mills

et al. 2020

ACS Appl. Mater. Interfaces

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Planar cholesteric liquid crystals (CLCs) are well known for having vibrant reflective coloration that is associated with the handedness and the pitch length of the helicoidal twist of the liquid crystalline molecules. If one observes these films at oblique angles, the reflected colors blue-shift with increasing angles from normal. On the other hand, uniform lying helix (ULH) CLCs, where the helicoidal axis lies in the plane of the substrate, are well-known but are not typically associated with vibrant colors. Here, we examine the unique optical properties of CLCs at oblique incidence angles, specifically the spectral and polarization changes associated with switching between planar and ULH CLCs for various incidence angles. At small angles of incidence (0°< ψ < 45°, where ψ is the angle of incidence relative to the surface normal at the substrate−CLC interface), the electrically driven helical reorientation from planar to ULH results in a blue-shifting of the color and circularly polarized to unpolarized switching behavior. At large angles (45°< ψ < 90°), the behavior is reversed, with a red-shifting color change occurring and the polarization switching from unpolarized to circularly polarized. Modeling of the light propagation through ULH CLCs is used to confirm the change in position and polarization characteristic of the reflection band with incidence angle observed experimentally. This study provides a new perspective on ULH CLCs and reveals a unique reconfigurable angular chromaticity.

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Electro-optic characteristics of stabilized cholesteric liquid crystals with non-liquid crystalline polymer networks

et al. 2022

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Angular dependences of transmission spectra of chiral liquid crystals

Cited by 4 publications

References 14 publications

Electrical Control of Unpolarized Reflectivity in Polymer‐Stabilized Cholesteric Liquid Crystals at Oblique Incidence

Electrical Control of Unpolarized Reflectivity in Polymer‐Stabilized Cholesteric Liquid Crystals at Oblique Incidence

A Different Perspective on Cholesteric Liquid Crystals Reveals Unique Color and Polarization Changes

Electro-optic characteristics of stabilized cholesteric liquid crystals with non-liquid crystalline polymer networks

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