According to one aspect, the invention relates to a device (20, 50) for controlling the phase of an incident optical wavefront of wavelength comprised in a spectral band of given use, comprising a substrate (21) that is at least partially transparent in said spectral band and a set of strips (22i, 23i, 24i) arranged substantially perpendicularly to the surface of the substrate, characterized in that: said set of strips comprises an alternation of juxtaposed strips respectively made of a metal (22i), of a first dielectric (23i) and of at least one second dielectric (24i) different from the first dielectric, such as to form juxtaposed metal/multi dielectric/metal (MmultiDM) structures (Si) of subwavelength widths (wi), each structure forming a cavity having one or more propagation modes—the respective thicknesses of the strips made of the first dielectric and of the second dielectric(s) are adjusted in each of said MmultiDM structures to induce a local shift (ΔΦi) in the phase of the wavefront, the local phase shift being dependent on the effective index of the mode(s) able to propagate in said cavity.