Random 1D structures as filters for electrical and optical signals

We present experimental and theoretical studies of the transport properties of random 1D site potentials. The key result is that exponentially weak transmissivity of a disordered system may be modified by finite correlations. We show that the long-range correlations give rise to a continuum of extended states, which are separated from localized states by mobility edges. For energies (or frequencies) between the mobility edges, the disordered system is transparent, while it is not outside this interval. We propose to exploit this property for filtering of electrical and optical signals.