The present disclosure concerns a device for forming a field intensity distribution in the near zone, from a propagating electromagnetic waves which are incident on said device. The device comprises: at least one layer of dielectric material, having a first refractive index n1 with a surface having at least one abrupt change of level forming a step; an element having a second refractive index n2 lower than said first refractive index n1, which is in contact with said step; and wherein said step generates a beam which is tilted compared to a propagation direction of said electromagnetic waves, and said beam having a length comprised between ½λ_1 to 10λ_1, with λ_1 being a wavelength of said electromagnetic waves in said dielectric material.