Scattering matrix method for propagation of radiation in stratified media: attenuated total reflection studies of liquid crystals

Ko, D. Y. K.; Sambles, J. R.

doi:10.1364/josaa.5.001863

Cited by 241 publications

(122 citation statements)

References 5 publications

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“…The plane waves are then modulated by the wide angle and multiple beam interferences that arise from reflections onto the one-dimensional CLC stack. The reflection of plane waves with given k-vector and arbitrary polarization on the CLC stack is described by a matrix method [22]. First the power emitted by a unit dipole P (λ,α) in a given CLC stack is calculated for each angle and wavelength separately.…”

Section: B Plane Wave Expansion Simulationmentioning

confidence: 99%

Light emission from dye-doped cholesteric liquid crystals at oblique angles: Simulation and experiment

et al. 2012

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Dye-doped cholesteric liquid crystals with a helical pitch of the order of a wavelength have a strong effect on the fluorescence properties of dye molecules. This is a promising system for realizing tunable lasers at low cost. We apply a plane wave model to simulate the spontaneous emission from a layer of cholesteric liquid crystal. We simulate the spectral and angle dependence and the polarization of the emitted light as a function of the order parameter of the dye in the liquid crystal. Measurements of the angle dependent emission spectra and polarization are in good agreement with the simulations.

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Section: B Plane Wave Expansion Simulationmentioning

confidence: 99%

Light emission from dye-doped cholesteric liquid crystals at oblique angles: Simulation and experiment

et al. 2012

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“…In addition in real liquid crystal cells significant variations of the director twist and tilt through the layer will generally exist and these very important situations have to be considered. Thus for most investigation of liquid crystal waveguides simple analytic expressions tend not to be utilised, instead full multilayer optics theory [22][23][24][25] is used to model reflectivities, transmissivities and optical field profiles. This then allows the incorporation of the full optical tensor with a spatially varying (through the cell) director profile, allowing the prediction of optical response functions which may be used to compare with data.…”

Section: The Field Distributions Of Optical Guided Modes [56]mentioning

confidence: 99%

Guided mode studies of liquid crystal layers

Yang¹,

Sambles²

2003

Nanotechnology and Nano-Interface Controlled Electronic Devices

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“…All eight datasets for each time were then fitted to simultaneously using a multilayer optics model based on a 4 ϫ 4 Berreman matrix 12 with the best-fit determined from a least-squares fitting routine. As the optical parameters for the ITO, polyimides, and liquid crystal had been previously determined, these were fixed, and only the tilt profile ͑described mathematically by a Bezier function to allow good control over the start and end tilt points, as well as the form of the profile in the centre of the cell͒ was allowed to vary.…”

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confidence: 99%

Rapid switching in a dual-frequency hybrid aligned nematic liquid crystal cell

Jewell

Taphouse

Sambles

2005

Applied Physics Letters

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We report the optical characterization of a dual-frequency hybrid aligned nematic ͑HAN͒ liquid crystal cell driven between two states using a multiple-frequency sinusoidal pulse. The complex dynamic director structure formed during the fast switching process is resolved in unprecedented detail on a submillisecond time scale. The results reveal backflow effects and a total switching time that is substantially faster than that achievable with conventional HAN cells. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1992672͔To allow liquid crystal devices to maintain their position as the primary flat-panel display, the quality of video rate images, dominated by the switching speed of the pixels, must be improved. This fundamental limitation is dictated by the viscoelastic properties of the liquid crystal, and to overcome this problem both the structure of the liquid crystal cell and the material itself must be considered.One potential fast-switching structure is the hybrid aligned nematic ͑HAN͒ cell, which has already been demonstrated as a commercially significant geometry in the new generation of zenithal bistable devices. 1 A HAN cell has homogeneous alignment on one surface and homeotropic alignment on the other. To a first approximation, this geometry offers equal bias to both homogeneous and homeotropic alignment, resulting in a near-linear variation in tilt with distance through the cell. On application of a voltage across a HAN cell, a thresholdless distortion can readily be produced, aligning the director either homeotropically or homogeneously depending on the sign of the dielectric anisotropy of the nematic liquid crystal used. 2,3 An interesting possibility arises when a HAN structure is combined with a dualfrequency liquid crystal; 4,5 these materials have a high dielectric dispersion where the dielectric anisotropy, ⌬ ͑f͒ = ʈ ͑f͒ − Ќ ͑f͒, is frequency dependent, resulting in a change in sign at the crossover frequency f co , where ⌬ ͑f co ͒ = 0. Certain dual-frequency materials are commercially available in which f co occurs at a few kHz and ⌬ ͑f͒ changes significantly over the range 1 -100 kHz. In a dual-frequency HAN cell, the director can be driven between either homogeneous or homeotropic alignment with equal ease by applying an electric field across the sample at a frequency either above or below f co . 6 This provides a relatively straightforward means of switching the cell between the birefringent homogeneous alignment and the uniaxial homeotropic alignment, which are both optically very different from the relaxed 0 V state.Optical waveguide techniques have become one of the leading tools for the detailed measurement of the director profiles in numerous liquid crystal structures. 7-9 A modification to the synchronization of voltage application and data collection in the standard fully leaky guided mode ͑FLGM͒ technique 10 has now been implemented, allowing the director orientation during dynamic reorientation to be recorded on an unprecedented 2 s time scale. This time-resolved FLGM techni...

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Scattering matrix method for propagation of radiation in stratified media: attenuated total reflection studies of liquid crystals

Cited by 241 publications

References 5 publications

Light emission from dye-doped cholesteric liquid crystals at oblique angles: Simulation and experiment

Light emission from dye-doped cholesteric liquid crystals at oblique angles: Simulation and experiment

Guided mode studies of liquid crystal layers

Rapid switching in a dual-frequency hybrid aligned nematic liquid crystal cell

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