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Dynamics of weak and strong localization of light in a correlated 2D photonic disorder

Julien Armijo

Jeudi 21 juillet 2016

à 11h, en salle C. BROT

In this seminar, I will present recent studies of light propagation in 2D photonic disorders. In photorefractive crystals, we photo-induce random potentials with adjustable strength VR and correlation length σR using a speckle-like beam controlled with a spatial light modulator (SLM) [1-2]. The refractive index inside the crystal is random in the transverse plane, but longitudinally invariant in the direction of propagation of the probe beam. Using also an SLM, probe beams are prepared as controlled wavepackets that are sent in the disorder, and then observed at the crystal output face with real and Fourier space imaging. For quasi-plane wave with controlled transverse momentum, we observe in Fourier space the formation of a ring of elastic scattering, with anisotropies governed by disorder correlations, and a peak of coherent back-scattering (CBS), whose dynamics is studied [3]. For wavepackets focused at the crystal input face, expanding inside the transverse disorder, we observe in real space exponential Anderson localization of light, with peculiar patterns governed by the correlations of our disorder. We compare our observations to simulations using a novel calibration technique for the refractive index [4].

[1] Boguslawski, M., S. Brake, J. Armijo, F. Diebel, P. Rose, and C. Denz, “Analysis of transverse Anderson localization in refractive index structures with customized random potential,” Opt. Express, Vol. 21, 31,713–31,724, 2013.

[2] Allio, R., D. Guzman-Silva, C. Cantillano, L. Morales-Inostroza, D. Lopez-Gonzalez, S. Etcheverry, R. A. Vicencio, and J. Armijo, “Photorefractive writing and probing of anisotropic linear and nonlinear lattices,” J. Opt., Vol. 17, 025,101, 2015.

[4] J. Armijo and R. Allio, Observation of coherent back-scattering and its dynamics in a transverse 2D photonic disorder : from weak to strong localization, arxiv:1504.07340

[3] J. Armijo, R. Allio, and C. Mejia-Cortes, “Absolute calibration of the refractive index in photo-induced photonic lattices,” Opt. Express, Vol. 22, 20,574–20,587, 2014.