by D. Capeta, J. Radic, A. Szameit, M. Segev and H. Buljan.
Physical Review A 84, 011801(R) 2011.
Lately, I have been reading a lot about waveguides. It is interesting how one can classically simulate—this word is en vogue—condensed matter and relativistic phenomena with light in coupled waveguides.
Last week, I found this this rapid communication. In it, Capeta et. al. focus in Anderson localization—first described in disordered electronic systems and optically realized a few years ago—. Their particular crux goes around these facts:
- Anderson localization arises from the interference among scattering events in a disordered medium.
- In an optical realization one can use incoherent light; say, light from a spceckle source.
- But incoherent light can be seen as an infinite superposition of coherent modes and each should Anderson localize in a sufficiently disordered medium.
So, Does incoherent light localize in the presence of disordered media?
Capeta et. al. find their answer: Yes, it does localize after a sufficiently long propagation time both numerically and experimentally; the first by studying the mutual coherence function of a spatially incoherent optical beam propagating through a photonic waveguide lattice where the refraction index of individual waveguides varies randomly, the second by following the intensities of the beam at different propagation distances on the lattice. They cover both finite and infinite cases through finite realizations with reflective and absorbing boundaries. They find the exponential decaying tail of Anderson localization even with instantaneous realizations of the incoherent fields.
It is a nicely written paper, simple to read and follow. If you are interested in what has been going around optical realizations of Anderson localization, the references have a nice survey on the topic.
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