共查询到20条相似文献,搜索用时 0 毫秒
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《Comptes Rendus Physique》2009,10(10):957-963
We present a theoretical and numerical analysis of pulse propagation in a semiconductor photonic crystal waveguide with embedded quantum dots in a regime where the pulse is subjected to both waveguide and material dispersion. The group index and the transmission are investigated by finite-difference-time-domain Maxwell–Bloch simulations and compared to analytic results. For long pulses the group index (transmission) for the combined system is significantly enhanced (reduced) relative to slow light based on purely material or waveguide dispersion. Shorter pulses are strongly distorted and depending on parameters broadening or break-up of the pulse may be observed. The transition from linear to nonlinear pulse propagation is quantified in terms of the spectral width of the pulse. To cite this article: T.R. Nielsen et al., C. R. Physique 10 (2009). 相似文献
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E. V. Aksenova A. A. Karetnikov A. P. Kovshik E. V. Kryukov V. P. Romanov 《Optics and Spectroscopy》2008,104(6):909-919
The particular features of the propagation of light in uniaxial chiral liquid crystals with a large pitch of the spiral are considered. There exist forbidden zones in these systems for fairly large angles of incidence of an extraordinary ray. On the one hand, this results in an efficient reflection of the wave from the zone boundary, and, on the other hand, this causes the wave to decay inside the zone. A case of narrow forbidden zones is studied, and it is shown that optical effects that arise upon propagation of rays near turning points are equivalent to the tunnel and over-barrier reflection effects. The angular dependences of the intensities of rays that were refracted in a forbidden zone and transmitted through it are calculated. The percolation effect is experimentally studied in a mixture of a nematic liquid crystal with a chiral addition. The intensity of a transmitted extraordinary ray is studied as a function of the angle of incidence, which determines the width of the forbidden zone. Both the over-barrier reflection and the percolation effects are observed. The calculation results are shown to agree with experiment. 相似文献
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A. Lakhtakia 《Applied physics. B, Lasers and optics》1985,36(3):163-165
A fourth-order wave equation is derived to study the propagation of an electromagnetic (EM) wave in a medium composed of chiral objects. This approximate wave equation does not reflect the handedness of the medium directly, which is more readily apparent, however, in a pair of two coupled second-order wave equations obtaineden route. 相似文献
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The propagation of electromagnetic waves in infinite, semiinfinite, and laminar chiral structures is investigated, along with
the diffraction of electromagnetic waves on semiinfinite objects in a chiral medium and three-dimensional objects consisting
entirely or partially of chiral materials. Particular attention is paid to diffraction on three-dimensional uniform chiral
bodies and ideally conducting bodies covered by chiral shells.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 50–61, August, 1998. 相似文献
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The spatial coherence of thermal light propagated through passive bounded media is measured. It is found that specular reflection at the boundaries enhances the degree of coherence. This result has considerable implications for the spatial coherence of light from laser and amplified spontaneous emission (A.S.E.) systems. 相似文献
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A. M. Fedorovskii V. I. Gorbachev V. A. Shcheglov A. A. Stepanov S. V. Troshchenkov 《Journal of Russian Laser Research》1996,17(2):101-108
The problem of laser-radiation propagation in media with small-scale periodic phase inhomogeneities is considered analytically. Relying on our analytical treatment and numerical calculations performed in the diffraction approximation, we demonstrate the effect of periodic self-reproduction of the field structure of radiation during its propagation in media with small-scale periodic inhomogeneities, which is similar to the Talbot effect in a homogeneous medium. 相似文献
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E. V. Aksenova B. B. Divinskii A. A. Karetnikov N. A. Karetnikov A. P. Kovshik E. V. Kryukov V. P. Romanov 《Journal of Experimental and Theoretical Physics》2014,118(2):323-332
We investigate the propagation of the extraordinary ray in a cell with a chiral liquid crystal at oblique incidence. For a 180° twist cell, we study the dependence of the minimum incidence angle at which the light does not yet pass through the cell on the applied voltage. The orientational structure of a liquid crystal in an external electric field has been calculated by directly minimizing the free energy. This has allowed the ray trajectories and the limiting refraction angles to be determined. The results of our calculations are consistent with the experiment. We show that allowance for the electric field nonuniformity in a chiral system is important for agreement between theory and experiment. 相似文献
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By the method of “short optical paths”, the dynamics of photon antibunching is shown to depend on the polarisation state of the photons and their two-photon absorption in an isotropic medium. In the case of self-induced optical birefringence, a change in helicity of the elliptically polarized beam or a change in sign of the angle between the large semi-axis of the ellipse and the analyzer causes a reversal of antibunching into bunching. Linear and circular polarisation of the photons are discussed as well for antibunching related with two-photon absorption, defined by the imaginary part of the molecular hyperpolarizability tensor. 相似文献
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M. Z. Harutyunyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2007,42(3):101-106
The interaction of light with a layer of a chiral photonic crystal is considered. Features of the Borrmann effect at a strong anisotropy are studied. The natural polarizations are considered, and it is shown that in the limit δ << 1 (δ = (?1 ? ?2)/(?1 + ?2), where ?1 and ?2 are the principal values of the dielectric permittivity tensor in the plane perpendicular to the medium axis) these polarizations are orthogonal and quasi-circular, while in the limit δ >> 1 they are orthogonal but linearly polarized. It is established that in the general case the chiral photonic crystals show a complete selectivity not to the circular polarizations (as at δ << 1), but to the natural polarizations. 相似文献
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Numerical analysis of optical propagation in highly scattering media is investigated when light is normally incident to the surface and re-emerges backward from the same point. This situation corresponds to practical light scattering setups, such as in optical coherence tomography. The simulation uses the path-length-assigned Monte Carlo method based on an ellipsoidal algorithm. The spatial distribution of the scattered light is determined and the dependence of its width and penetration depth on the path-length is found. The backscattered light is classified into three types, in which ballistic, snake, and diffuse photons are dominant. 相似文献
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Monte Carlo (MC) method is a statistical method for simulating photon propagation in media in the optical molecular imaging field.However,obtaining an accurate result using the method is quite time-consuming,especially because the boundary of the media is complex.A voxel classification method is proposed to reduce the computation cost.All the voxels generated by dividing the media are classified into three types (outside,boundary,and inside) according to the position of the voxel.The classified information is used to determine the relative position of the photon and the intersection between photon path and media boundary in the MC method.The influencing factors and effectiveness of the proposed method are analyzed and validated by simulation experiments. 相似文献
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In this paper, we present solutions for the nonlinear Schrödinger (NLS) equation with spatially inhomogeneous nonlinearities describing propagation of light in nonlinear media, under two sets of transverse modulation forms of inhomogeneous nonlinearity. The bright soliton solution and Gaussian solution have been obtained for one set of inhomogeneous nonlinearity modulation. For the other, bright soliton solution, black soliton solution and the train solution have been presented. Stability of the solutions has been determined by exact soliton solutions under certain conditions. 相似文献
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Summary The scattering of electromagnetic waves in chiral (optically active) media from chiral spheres is studied. Mie-scattering
techniques are used to find the exact solution for plane-electromagnetic-wave scattering from a chiral sphere of arbitrary
size in an infinitely extended chiral medium of arbitrarily different permeability, permittivity, and chirality, and the scattering
and extinction efficiencies for chiral spheres in chiral media are derived. Special cases of achiral exterior medium-chiral
sphere and achiral exterior medium-achiral scatterer are considered and in the latter case well-known results of Mie scattering
are recovered. Simplified results for small spheres are also found for the limit of Rayleigh scattering. 相似文献