Simulation of radiation transfer and coherent backscattering in nematic liquid crystals

Abstract

We consider the multiple scattering of light by fluctuations of the director in a nematic liquid crystal. Using methods of numerical simulation the peak of the coherent backscattering and the coefficients of anisotropic diffusion are calculated. The calculations were carried out without simplifying assumptions on the properties of the liquid crystal. The process of multiple scattering was simulated as a random walk of photons in the medium. We investigated in detail the transition to the diffusion regime. The dependence of the diffusion coefficients on the applied magnetic field and the wavelength of light were studied. The results of simulation showed a non-monotonic dependence of the diffusion coefficients on the external magnetic field. A qualitative explanation of this behavior was suggested using a simple scalar model. For calculation of the peak of the coherent backscattering we used the semianalytical approach as long as in nematic liquid crystals this peak is extremely narrow. The parameters of backscattering peak and of diffusion coefficients which were found in numerical simulations were compared with the experimental data and the results of analytical calculation.

Simulation of multiple scattering in the systems with complicated phase function

“…We used the obtained interpolations in order to study the radiative transfer and coherent effects in NLC [21]. (Fig.…”

Optical anisotropy measurement in normal and cancerous tissues: backscattering technique

“…In the case of epithelial tissues, anisotropic constituents are columnar cells. The aligned columnar cells have scattering properties similar to the nematic liquid crystal (NLC) molecules which become aligned under the applied magnetic fields [17]. In the stage of dysplasia, cell architecture and orientation undergo drastic changes as graphically represented in Fig.…”

“…regarding any direction in x-y plane [21][22][23]. Numerical simulations [14,17] as well as the experimental studies of disordered media containing aligned cylindrical microstructures with anisotropic polarizability such as nematic liquid crystals [24], etched gallium phosphide samples [25]and biological tissues having micro fibers such as muscle, skin, bone and tooth ascertain anisotropic diffusion of light [12,26]. As a result, it is expected that the optical anisotropy of the media causes the asymmetry of the backscattering cone, and therefore, the FWHM dependence on the direction of determination in x-y plane.…”

Exact classical stochastic representations of the many-body quantum dynamics

“…Having described the general form for all the ingredients in our stochastic representation, let us now discuss under what conditions we can obtain the master equation (8), and when it represents indeed the exact quantum dynamics given by the quantum Liouville equation (3). We have discussed the representation of the right hand side of Eq.…”

“…V. P. Romanov, to whose memory is devoted the current issue, contributed to this school by his works on stochastics aspects of light propagation in fluctuating nematic liquid crystals [1][2][3].…”