摘要:

In surface stabilised ferroelectric liquid crystal (SSFLC) cells driven by low voltages, typically below 10V, it is observed that domains of the switched state nucleate and grow, merging to fill the cell. A model of domain nucleation in SSFLCs is proposed, which considers a nucleation site as a local absence of the chevron interface torque. The model is implemented in a two-dimensional simulation of the SSFLC SCE-8 in a chevron configuration with C2 alignment. It is shown to behave realistically over the voltage range 2-10V by comparison with experimental results.

ISSN:1058-725X    

DOI:10.1080/10587259508033557

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A reasonably general model of a liquid crystal is achieved by a continuum consisting of microscopic rigid bodies. Within this model it is possible to deal with chiral molecules as well as simple rod-like particles forming a conventional nematic liquid crystal. The configuration space of a rigid body is the rotation group SO(3); the configuration space of a “nematic” is - with regard to the head-tail symmetry - the projective plane P(2). By replacing both manifolds by their universal coverings (S3and S2, resp.) the internal symmetry of the fluid can be represented by a generalized (non-normalized) director. Within this mathematical framework mesoscopic balance equations are formulated which are applicable in the biaxial case of chiral molecules and in the uniaxial case of rod-like particles. Finally it is shown how constitutive equations can be derived by calculating averages of mesoscopic quantities with respect to an orientation distribution function which characterizes the orientational order of the liquid crystal.

ISSN:1058-725X    

DOI:10.1080/10587259508033558

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

New energetic effects for cholesteric liquid crystals subjected to orientational deformation such as the heat production or absorption at isothermal deformation, the chemical potential changing of multicomponent cholesterics and the temperature variation at adiabatic deformation, the noticeable difference between the isothermal and adiabatic moduli of torsion are predicted. The theory of these effects is developed on the basis of the previously obtained thermodynamic relations for a deformed liquid crystal.

ISSN:1058-725X    

DOI:10.1080/10587259508033559

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The transmission of a LCD for normal incident light can be simply calculated by a clever use of the Jones calculus. Several cases are treated in different ways. The results for a few examples are compared with the more general simulations according to the 4 × 4 Berreman method, which also takes internal reflections into account. Our fast optical calculations are useful when predicted molecular distributions should be confronted with experimental optical spectra.

ISSN:1058-725X    

DOI:10.1080/10587259508033560

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A nondegenerate four-wave mixing (FWM) on a new type of Kerr nonlinearity determined by the layer deformations in smectic A liquid crystal (SmA) is considered. It is shown that in the case when the frequency difference of the coupled electromagnetic waves (EMW) is close to the frequency of the second sound (SS), a strong parametric coupling among EMW through the dynamic grating of layer deformations occurs. As a result EMW with the lowest frequency is amplified and EMW with the highest frequency is depleted, while the two EMW with the intermediate frequencies are compressed in space and their envelopes take the form of a spatial soliton. The explicit expressions of all amplitudes are calculated. The gain coefficient appears to be one order of magnitude greater than the one for stimulated scattering on an ordinary sound in organic liquids. The interaction of EMW with the specially selected frequencies and wave vectors gives rise to the analog of Brillouin enhanced FWM (BEFWM) resulting in the amplification of the phase-conjugate EMW. The additional components of the fundamental EMW and a spectrum of spatially localized Brillouin-like small harmonics with combination frequencies and wave vectors are generated due to the combined effect of the new kind of Kerr nonlinearity discussed and anisotropy of SmA. It is shown that the light generates spatially periodic hydrodynamic flow with the large-scale soliton-type envelopes. The light-induced layer deformations generate the high-frequency longitudinal electric field due to the flexoelectric effect. The spatial and temporal characteristics of the dynamic grating appears to be close to the experimental data.

ISSN:1058-725X    

DOI:10.1080/10587259508033561

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The self-focusing of a laser beam due to the Kerr nonlinearity caused by layer deformations in a smectic A liquid crystal (SmA) is considered. It is shown that for a sufficiently high intensity the beam undergoes self-trapping forming a spatial soliton. The same mechanism is responsible for the self-trapping of a surface-guided light wave at the interface of a linear medium and SmA. Numerical estimations show that the new Kerr nonlinearity is approximately 10 times greater than a nonlinearity caused by bulk compression. Self-trapping effect may be observed in smectic A liquid crystal samples of a thickness of 0.01 cm and at a light beam power of an order of magnitude of 0.002 MW.

ISSN:1058-725X    

DOI:10.1080/10587259508033562

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:1058-725X    

DOI:10.1080/10587259508033506

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor