A light-emitting device including at least a metal layer able to be heated and to propagate surface waves consecutive to the heating of the metal layer, with the metal layer being structured such that it comprises several diffraction patterns able to carry out a diffraction of the surface waves to free-space propagation modes, wherein a synthetic hologram is encoded such that a phase image of a pixel of the hologram is encoded by an offset in the position of one of the diffraction patterns, and a heater of the metal layer.