Numerical study of light correlations in a random medium close to the Anderson localization threshold

Chang, Shoou-Jinn; Taflove, Allen; Yamilov, Alexey; Burin, Alexander L.; Cao, Hui

doi:10.1364/ol.29.000917

Cited by 21 publications

(26 citation statements)

References 18 publications

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“…This fact makes analytical treatment of the problem difficult. In this work, following the same approach [10,17], we obtained numerically the full distribution of conductance in passive and active disordered waveguides with time reversal symmetry [7]. We demonstrate that the second moment…”

mentioning

confidence: 84%

“…The walls of the waveguide are metallic, and circular scattering particles are dielectric with refractive index n = 2. We use finite difference time domain method to calculate the response of our system to pulsed excitation, followed by Fourier transformation which gives us the desired continuous-wave response [17]. We have successfully used this method to study mesoscopic fluctuations and nonlocal correlations [10,11].…”

mentioning

confidence: 99%

“…Our numerical algorithm allows calculation of transport coefficients within a certain frequency range. This range is chosen narrow enough so that there is no appreciable change in physical parameters such as transport mean free path [17]. Therefore, we use the conductance at different frequencies to increase the number of entries in our statistical ensembles to about ∼ 10 5 .…”

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confidence: 99%

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Effect of amplification on conductance distribution of a disordered waveguide

Yamilov

Cao²

2006

Phys. Rev. E

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confidence: 84%

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Effect of amplification on conductance distribution of a disordered waveguide

Yamilov

Cao²

2006

Phys. Rev. E

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“…Conversely, it is an interesting fundamental question how AL of light, which has been understood [22,23] as a consequence of self-interference, is influenced by the coherent, stimulated amplification in the lasing state. The problem of the intensity distribution in a diffusive random laser has been attacked theoretically by phenomenological diffusion models [24] and numerical calculations in one [25,26] and two spatial dimensions [20,[27][28][29]. However, the experimentally observed decrease of the lasing spot size with increasing pump rate, has not been explained so far.…”

Section: Introductionmentioning

confidence: 99%

Light transport and correlation length in a random laser

2009

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A random laser is a strongly disordered, laser-active optical medium. The coherent laser feedback, which has been demonstrated experimentally to be present in these systems beyond doubt, requires the existence of spatially localized photonic quasimodes. However, the origin of these quasimodes has remained controversial. We develop an analytical theory for diffusive random lasers by coupling the transport theory of the disordered medium to the semiclassical laser rate equations, accounting for (coherent) stimulated and (incoherent) spontaneous emission. From the causality of wave propagation in an amplifying, diffusive medium we derive a novel length scale which we identify with the average mode radius of the lasing quasi-modes. We show that truly localized modes do not exist in the system without photon number conservation. However, we find that causality in the amplifying medium implies the existence of a novel, finite intensity correlation length which we identify with the average mode volume of the lasing quasimodes. We show further that the surface of the laser-active medium is crucial in order to stabilize a stationary lasing state. We solve the laser transport theory with appropriate surface boundary conditions to obtain the spatial distributions of the light intensity and of the occupation inversion. The dependence of the intensity correlation length on the pump rate agrees with experimental findings.

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“…The statistics of field and intensity are therefore independent of position on the output surface. The degree of correlation, κ, which is the fractional correlation of fluctuations in intensity at points at which the field correlation function vanishes, is equal to var(s a ), κ = var(s a ) [15][16][17][18][19]. The localization transition between waves that extend throughout the sample and waves that are exponentially peaked within it occurs at g ~ 1.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic fluctuations, correlation and localization in the time domain

Genack

Chabanov

et al. 2005

Complex Mediums VI: Light and Complexity

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In this paper, we attempt to find a unified framework in which the statistics of wave propagation in random media can be understood as strengths of scattering and absorption increase. First, we discuss the weak scattering, diffusive limit without absorption. In this limit, the suppression of transmission by weak localization, the distribution of total transmission and the intensity correlation functions with displacement and polarization rotation are all described in terms of the dimensionless conductance so that these effects are explicitly linked. When absorption is introduced, the dimensionless conductance can no longer serve as a fundamental scaling parameter, but the variance of the total transmission is still able to chart the changing statistical character of propagation and localization with sample size. By examining transport at a fixed time following pulsed excitation, the affect of absorption can be removed while the growing impact of localization can be clearly discerned. The functional form of probability distributions of intensity and total transmission and of the spatial and polarization intensity correlation functions in the time domain are the same as in the frequency domain. The connection of mesoscopic fluctuations to localization can be seen in the spectral correlation function of the field, which is the Fourier transform of average pulsed transmission. The spectral field correlation function can be expressed as a product of the correlation function of the field normalized to the average amplitude in a given configuration and of the square root of the total transmission.

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Numerical study of light correlations in a random medium close to the Anderson localization threshold

Cited by 21 publications

References 18 publications

Effect of amplification on conductance distribution of a disordered waveguide

Effect of amplification on conductance distribution of a disordered waveguide

Light transport and correlation length in a random laser

Electromagnetic fluctuations, correlation and localization in the time domain

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