Localized mode hybridization by fine tuning of 2D random media

Abstract

We study numerically interaction of spatially localized modes in strongly scattering two-dimensional media. We move eigenvalues in the complex plane by changing gradually the index of a single scatterer. When spatial and spectral overlap is sufficient, localized states couple and avoided level crossing is observed. We show that local manipulation of the disordered structure can couple several localized states to form an extended chain of hybridized modes crossing the entire sample, thus changing the nature of certain modes from localized to extended in a nominally localized disordered system. We suggest such a chain is the analog in 2D random systems of the 1D necklace states, the occasional open channels predicted by J.B. Pendry through which the light can sneak through an opaque medium.