A new solid-state Wavelength-Selective Switch (WSS) based on a Programmable Micro-Diffractive Grating (PMDG) fabricated over a Lithium-Niobate (LiNbO3) substrate is presented, and its operation described. The device consists of a periodic arrangement of ridge waveguides whose optical phase delay can be individually or collectively tuned through the electro-optics (Pockels) effect. Each waveguide is patterned with a metal electrode and connected to an external microprocessor-based driving unit. By appropriately programming the phase shift induced on each waveguide, the far-field diffraction pattern of the grating can be shaped in order to implement complex all-optical signal processing functions, such as 1-to-M demultiplexing, beam splitting, beam steering or wavelength-selective filtering. Once integrated within a telecommunications infrastructure, this component can clearly enhance the level of flexibility …