Electro-optical modulator and a method for obtaining an electro-optical modulator

An electro-optical modulator, comprising:

• a semiconductor substrate;
• at least first and second electrodes distanced from each other along an X-direction;
• an optical waveguide embedded within and/or arranged on said semiconductor substrate, an upper face of said optical waveguide being located at, below or above a location between said first and second electrodes, along said X-direction, wherein said optical waveguide longitudinally extends along at least a direction transversal to said X-direction;
• a bottom graphene sheet arranged and extending along said X-direction over at least a portion of the upper face of the semiconductor substrate, with a first end electrically connected to said first electrode and without the bottom graphene sheet reaching the second electrode;
• a sheet of a first dielectric material extending over said bottom graphene sheet;
• a top graphene sheet arranged and extending along said X-direction over at least a portion of said sheet of a first dielectric material, with a first end electrically connected to said second electrode and without the top graphene sheet reaching the first electrode;
• and
• a second dielectric material, which is a two-dimensional material with at least dielectric properties different to the dielectric properties of said first dielectric material, said second dielectric material covering:
• upper and bottom faces of said top graphene sheet and/or an upper face of said bottom graphene sheet;
• or
• upper and bottom faces of said top graphene sheet and/or both upper and bottom faces of said bottom graphene sheet;
• wherein at least one of said top and bottom graphene sheets extends along said X-direction:
• above part of the width of the optical waveguide, wherein said part ranges from 50% to 100% of the width of the optical waveguide;
• or
• completely above the whole width of the optical waveguide, and beyond through a respective further projecting portion with a length, along the X direction, of up to 25% of the optical waveguide width.