Hanbury Brown and Twiss Correlations of Anderson Localized Waves
  When light waves propagate through disordered photonic lattices, they can eventually become localized due to multiple scattering effects. Here we show experimentally that while the evolution and localization of the photon density distribution is similar in the two cases of diagonal and off-diagonal disorder, the density-density correlation carries a distinct signature of the type of disorder. We show that these differences reflect a symmetry in the spectrum and eigenmodes that exists in off-diagonally disordered lattices but is absent in lattices with diagonal disorder. 
Y. Lahini, Y. Bromberg, Y. Shechtman, A. Szameit, D. N.   Christodoulides, R. Morandotti, and Y. Silberberg
cond-mat.dis-nn