Chiral Optical Tamm States at the Interface between a Dye-Doped Cholesteric Liquid Crystal and an Anisotropic Mirror

The resonant splitting of optical Tamm state numerically is demonstrated. The Tamm state is localized at the interface between a resonant chiral medium and a polarization-preserving anisotropic mirror. The chiral medium is considered as a cholesteric liquid crystal doped with resonant dye molecules. The article shows that the splitting occurs when dye resonance frequency coincides with the frequency of the Tamm state. In this case the reflectance, transmittance, and absorptance spectra show two distinct Tamm modes. For both modes, the field localization is at the interface between the media. The external field control of configurable optical and structural parameters paves the way for use in tunable chiral microlaser.

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Metal–Dielectric Polarization-Preserving Anisotropic Mirror for Chiral Optical Tamm State

Nanomaterials ◽

10.3390/nano12020234 ◽

2022 ◽

Vol 12 (2) ◽

pp. 234

Author(s):

Natalya V. Rudakova ◽

Rashid G. Bikbaev ◽

Pavel S. Pankin ◽

Stepan Ya. Vetrov ◽

Ivan V. Timofeev ◽

...

Keyword(s):

Liquid Crystal ◽

Numerical Study ◽

Cholesteric Liquid Crystal ◽

Q Factor ◽

Dielectric Polarization ◽

Localized State ◽

Number Of Layers ◽

Tamm State ◽

The Difference

This numerical study demonstrates the possibility of exciting a chiral optical Tamm state localized at the interface between a cholesteric liquid crystal and a polarization-preserving anisotropic mirror conjugated to a metasurface. The difference of the proposed structure from a fully dielectric one is that the metasurface makes it possible to decrease the number of layers of a polarization-preserving anisotropic mirror by a factor of more than two at the retained Q-factor of the localized state. It is shown that the proposed structure can be used in a vertically emitting laser.

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Regular and chaotic structures of the cholesteric liquid crystal in an external field

Physics Letters A ◽

10.1016/0375-9601(84)90490-0 ◽

1984 ◽

Vol 106 (1-2) ◽

pp. 47-50 ◽

Cited By ~ 2

Author(s):

V.V. Beloshapkin ◽

A.G. Tret'yakov

Keyword(s):

Liquid Crystal ◽

External Field ◽

Cholesteric Liquid Crystal

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Phase diagrams of mixtures of a polymer and a cholesteric liquid crystal under an external field

The Journal of Chemical Physics ◽

10.1063/1.4901085 ◽

2014 ◽

Vol 141 (18) ◽

pp. 184903 ◽

Cited By ~ 8

Author(s):

Akihiko Matsuyama

Keyword(s):

Liquid Crystal ◽

External Field ◽

Phase Diagrams ◽

Cholesteric Liquid Crystal

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Chiral Optical Tamm States at the Interface between an All-Dielectric Polarization-Preserving Anisotropic Mirror and a Cholesteric Liquid Crystal

Crystals ◽

10.3390/cryst9100502 ◽

2019 ◽

Vol 9 (10) ◽

pp. 502 ◽

Cited By ~ 4

Author(s):

Natalya V. Rudakova ◽

Ivan V. Timofeev ◽

Rashid G. Bikbaev ◽

Maxim V. Pyatnov ◽

Stepan Ya. Vetrov ◽

...

Keyword(s):

Liquid Crystal ◽

Photonic Bandgap ◽

Cholesteric Liquid Crystal ◽

Hybrid Structure ◽

Dielectric Polarization ◽

Transmission Resonance ◽

Localized State ◽

Sensing Applications ◽

Dielectric Mirror ◽

Tamm State

As a new localized state of light, the chiral optical Tamm state exists at the interface between a polarization-retaining anisotropic mirror and a substance with optical activity. Considering a hybrid structure comprising a metal-free polarization-preserving mirror and a cholesteric liquid crystal, we highlight the high Q factor arising from the all-dielectric framework. The intensity of localized light decreases exponentially with increasing distance from the interface. The penetration of the field into the cholesteric liquid crystal is essentially prohibited for wavelengths lying in the photonic bandgap and close to the cholesteric pitch length. The dielectric mirror has its own photonic bandgap. The energy transfer along the interface can be effectively switched off by setting the tangential wave vector to zero. The spectral behavior of the chiral optical Tamm state is observed both as reflection and transmission resonance. This Fano resonance is analogous to the Kopp–Genack effect. Our analytics are well in line with precise calculations, which may pave a new route for the future development of intelligent design for laser and sensing applications.

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Uniqueness of director configuration states for liquid crystals in the case of weak anchoring

IMA Journal of Applied Mathematics ◽

10.1093/imamat/hxz013 ◽

2019 ◽

Vol 84 (4) ◽

pp. 748-762

Author(s):

Carlo Greco

Keyword(s):

Magnetic Field ◽

Liquid Crystal ◽

External Field ◽

Thin Layer ◽

Elastic Constants ◽

Cholesteric Liquid Crystal ◽

Stable Configuration ◽

Director Field ◽

Critical Thresholds ◽

Bounding Surfaces

Abstract In a thin layer of liquid crystal the configuration of the director field depends on the interaction between the elastic properties of the material, the thickness $d$ of the layer, the boundary conditions and the external fields that may have been applied. Suitable combinations of these factors can give rise to distorted configurations (Freedericksz transitions). In this paper we assume the Oseen-Frank model for the energy and that the director field depends only on the direction orthogonal to the layer; we assume also weak anchoring conditions at the two bounding surfaces, and we mainly study the problem of uniqueness of such distorted configurations. More precisely, we first consider the nematic case in the presence of a magnetic field $\mathbf H$, and we prove the uniqueness of the stable configuration provided the magnitude of $\mathbf H$ is between two critical thresholds, simplifying some results already known in the literature, and calculating explicitly the critical thresholds. Then we study the case of a cholesteric liquid crystal without external field. In this case the director field tends to form a right-angle helicoid around a twist axis orthogonal to the layer, and we have distorted configurations (namely oblique helicoid) for suitable value of $d$. Also in this case, with suitable restrictions on the elastic constants in the Oseen-Frank energy, we find two critical thresholds for $d$, and we prove the existence of only one stable director configuration if $d$ is between them.

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A Dye-Dispersed Liquid Crystal Smart Reflector

MRS Proceedings ◽

10.1557/proc-360-97 ◽

1994 ◽

Vol 360 ◽

Author(s):

Ching-Chao Chang ◽

Franklin Lonberg ◽

Robert B. Meyer

Keyword(s):

Liquid Crystal ◽

Light Intensity ◽

Negative Feedback ◽

Incident Light ◽

Cholesteric Liquid Crystal ◽

Dye Molecules ◽

Incident Light Intensity ◽

Average Temperature ◽

Pitch Length

AbstractWe report a liquid crystal smart reflector, consisting of a cholesteric liquid crystal doped with dye. Light entering the liquid crystal is absorbed by the dye, generating heat which raises the average temperature of the liquid crystal. This in turn changes the pitch length of the cholesteric liquid crystal, causing an increase in its reflectivity, and thus reducing the amount of light absorbed by the dye molecules. A negative feedback stabilized condition is reached, in which the reflectivity is proportional to the incident light intensity. This effect is demonstrated both theoretically and experimentally.

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