Abstract: A waveguide is provided on which an electromagnetic wave impinges, the electromagnetic wave having a wavelength ? included in a given interval ?? of interest centered on a ?centr. The waveguide comprises a film defining a surface on a plane on which the electromagnetic waves are apt to impinge, having a thickness in a direction substantially perpendicular to the surface, the film being realized in a material having a first refractive index; a plurality of scatterers being randomly distributed in two directions in at least a portion of the surface of the film, the scatterers having a substantially constant cross section along said substantially perpendicular direction. The scatterers are realized in a material having a second refractive index lower than the first refractive index, wherein the wavelength of the incident electromagnetic waves is comprised between 0.

Abstract: A waveguide is provided on which an electromagnetic wave impinges, the electromagnetic wave having a wavelength ? included in a given interval ?? of interest centered on a ?centr. The waveguide comprises a film defining a surface on a plane on which the electromagnetic waves are apt to impinge, having a thickness in a direction substantially perpendicular to the surface, the film being realized in a material having a first refractive index; a plurality of scatterers being randomly distributed in two directions in at least a portion of the surface of the film, the scatterers having a substantially constant cross section along said substantially perpendicular direction. The scatterers are realized in a material having a second refractive index lower than the first refractive index, wherein the wavelength of the incident electromagnetic waves is comprised between 0.