Coherent Backscattering and Anderson Localization of Light

Aegerter, Christof M.; Maret, Georg

doi:10.1016/s0079-6638(08)00003-6

Cited by 53 publications

(59 citation statements)

References 113 publications

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“…A number of techniques exist which provide a single measurement of the scattering properties of a given sample volume. Diffusing Wave Spectroscopy (DWS) [9] (or "Diffuse Transmission Spectroscopy" [10]) and coherent backscattering [11] are such techniques that can measure the scattering strength of a diffusive medium through determination of a characteristic parameter known as the transport mean free path l * or the reduced scattering coefficient μ t = 1/l * . Light reflected from a turbid medium has typically entered the object up to a depth z of a (few times the) transport mean free path l * .…”

Section: Introductionmentioning

confidence: 99%

Rapid high resolution imaging of diffusive properties in turbid media

Scheffold¹,

Block²

2011

Opt. Express

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Abstract:We propose a laser speckle based scheme that allows the analysis of local scattering properties of light diffusely reflected from turbid media. This turbid medium can be a soft material such as a colloidal or polymeric material but can also be biological tissue. The method provides a 2D map of the scattering properties of a complex, multiple scattering medium by recording a single image. We demonstrate that the measured speckle contrast can be directly related to the local transport mean free path l * or the reduced scattering coefficient μ t = 1/l * of the medium. In comparison to some other approaches, the method does not require scanning (of a laser beam, detector or the sample itself) in order to generate a spatial map. It can conveniently be applied in a reflection geometry and provides a single characteristic value at any given position with an intrinsic resolution typically on the order of 5-50 μm. The actual resolution is however limited by the transport mean free path itself and can thus range from microns to millimeters.

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Section: Introductionmentioning

confidence: 99%

Rapid high resolution imaging of diffusive properties in turbid media

Scheffold¹,

Block²

2011

Opt. Express

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“…This is due to several factors such as a non-ideal point source, a finite sample cell size (which eliminates the possibility of long scattering paths), and the presence of closed loop scattering paths. 20,21 The resolution and quality of the image depends on several factors, such as the volume fraction of the scatterer ϕ, the diameter of the scatterer D, and the distance d. When the scatterer diameter D is fixed, low volume fraction ϕ (corresponding to a low number content) reduces the possibility of multiple scattering paths, and therefore resulting in a small enhancement factor. On the other hand, when the volume fraction is too large (corresponding to a large number content), the recurrent scattering leads to a reduction of the enhancement factor and an increase in the full width at halfmaximum (FWHM) of the PSF, 22 which lead to a decreasing image resolution.…”

Section: B Characterization and Optimizationmentioning

confidence: 99%

Lensless imaging based on coherent backscattering in random media

Yang

Hong

et al. 2014

AIP Advances

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We studied lensless imaging due to coherent backscattering in random media both theoretically and experimentally. The point spread function of the lensless imaging system was derived. Parameters such as the volume fraction of the scatterer in the random scattering medium, the diameter of the scatterer, the distance between the object to be imaged and the surface of the random scattering medium were optimized to improve the image contrast and resolution. Moreover, for complicated objects, high contrast and quality images were achieved through the high-order intensity correlation measurement on the image plane, which may propel this imaging technique to practical applications.

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“…However, it is long known that they are destructive for magnetic or spinorbit scattering since a rotation of 2π of the electron spins gives rise to a sign flip of the interference terms. In this case, one rather gets weak anti-localization effects as revealed by magneto-resistance measurements and suppression of the coherent backscattering (CBS) effect [23,26]. The very same situation happens in graphene [27][28][29][30] where the band structure induces two Berry monopoles of opposite charge located at the Dirac points, hence an effective magnetic field in momentum space.…”

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confidence: 94%

Momentum-space dynamics of Dirac quasiparticles in correlated random potentials: Interplay between dynamical and Berry phases

2014

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We consider Dirac quasi-particles, as realized with cold atoms loaded in a honeycomb lattice or in a π-flux square lattice, in the presence of a weak correlated disorder such that the disorder fluctuations do not couple the two Dirac points of the lattices. We numerically and theoretically investigate the time evolution of the momentum distribution of such quasi-particles when they are initially prepared in a quasi-monochromatic wave packet with a given mean momentum. The parallel transport of the pseudo-spin degree of freedom along scattering paths in momentum space generates a geometrical phase which alters the interference associated with reciprocal scattering paths. In the massless case, a well-known dip in the momentum distribution develops at backscattering (respective to the Dirac point considered) around the transport mean free time. This dip later vanishes in the honeycomb case because of trigonal warping. In the massive case, the dynamical phase of the scattering paths becomes crucial. Its interplay with the geometrical phase induces an additional transient broken reflection symmetry in the momentum distribution. The direction of this asymmetry is a property of the Dirac point considered, independent of the energy of the wave packet. These Berry phase effects could be observed in current cold atom lattice experiments.PACS numbers: 42.25. Dd, 37.10.Jk, 03.65.Vf, Introduction.-Topology and gauge fields, as exemplified by Chern numbers [1], Berry phases and curvatures [2], are key concepts at the heart of many condensed-matter phenomena [3,4]. One main reason is that Bloch's theorem introduces wave numbers k belonging to a parameter space with the topology of a torus, the Brillouin zone, and a set of periodic wave functions depending parametrically on k. Together they offer natural settings for bundles and connections [5]. With the recent advances in the generation of synthetic magnetic fields [6][7][8] and the ability to load independent or interacting bosons and/or fermions into two-dimensional optical lattices [9][10][11] where the relevant experimental parameters are perfectly under control, ultracold atoms have become versatile tools to explore directions borrowed from other fields like topological defects [12], color superfluidity [13], engineering and measuring non-zero momentum-space Berry curvatures [14] or creating quantum Hall states with strong effective magnetic fields [15][16][17][18].In this work, we consider the momentum space dynamics of Dirac quasi-particles [19][20][21], as found for example in graphene sheets, in the presence of a correlated and weak on-site disorder. A semi-classical approach shows that the dynamics of these quasi-particles is unaffected by the topology of the band structure as long as a net effective electric field is absent [4,22]. We go beyond this semi-classical approach to address the competition happening at short times between Berry phase effects induced by the Bloch states topology and dynamical coherent corrections to transport due to the interference associa...

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Coherent Backscattering and Anderson Localization of Light

Cited by 53 publications

References 113 publications

Rapid high resolution imaging of diffusive properties in turbid media

Rapid high resolution imaging of diffusive properties in turbid media

Lensless imaging based on coherent backscattering in random media

Momentum-space dynamics of Dirac quasiparticles in correlated random potentials: Interplay between dynamical and Berry phases

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