Electrically adjustable diffraction grating

An electrically adjustable diffraction grating for a waveguide, comprising;

• a substrate;
• an electrooptic structure extending over the substrate, said electrooptic structure comprising a waveguide having a propagation axis;
• a first and a second electrode structure for generating an electric field therebetween, said first and second electrode structures being disposed on opposite sides of the electrooptic structure and parallel to the propagation axis of the waveguide, the first electrode structure having an interdigitated configuration defining a plurality of fingers, where potentials V0 and V0+ΔV are applied to adjacent fingers of said first electrode structure and a potential is applied to the second electrode structure, so that the electric field generated between the first and second electrode structures induces a diffraction grating in the waveguide having a refractive index adjustable by varying V0 and ΔV and a spatial periodicity adjustable by varying ΔV.