Competition of different scattering mechanisms in a one-dimensional random photonic lattice

A one-dimensional random photonic lattice is studied both by the plane-wave method and by the transfer matrix approach for arbitrary contrast in its dielectric permittivity. The roles and competition of different scattering mechanisms such as Bragg diffraction, single-scatterer resonances, and Bragg remnants are investigated. The localization length, band-gap width, and middle-gap frequency are analyzed for both random and regular lattices in the higher-frequency bands. An analytical expression allowing the prediction of the existence of band-gap closing is obtained. It is shown not only that strong localization results from Bragg diffraction and disorder in the scatterers’ distribution but also that Bragg remnants produce localization for a medium with small contrast.