The invention discloses an electric tunable
grating coupler. The electric tunable
grating coupler comprises an SOI (
Silicon On Insulator) substrate, an
oblique incidence grating coupler, a P+ mixing area, an N+ mixing area, a pair of electrodes, a mode converter, a single mode
ridge waveguide and a substrate gold reflecting mirror, wherein the
SOI substrate comprises a
silicon substrate, an oxideburying layer and a top
silicon layer positioned at the upper position of the
SOI substrate; the
oblique incidence grating coupler is positioned on the top
silicon layer positioned on the
SOI substrate; the P+ mixing area is positioned in a panel area at one side of the
oblique incidence grating coupler; the N+ mixing area is positioned in the panel area at the other side of the oblique incidencegrating coupler; the electrodes are positioned at the upper positions of the P+ mixing area and the N+ mixing area, are respectively connected with the P+ mixing area and the N+ mixing area through
metal contact through holes and are used for loading electric signals; one end of the mode converter is provided with a wide
waveguide, the mode converter is positioned at one end of the oblique incidence grating coupler, and the end of the mode converter, which is provided with the wide
waveguide, is coupled with one end of the oblique incidence grating coupler; the single mode
ridge waveguide andthe oblique incidence grating coupler are respectively positioned at two ends of the mode converter; and the substrate gold reflecting mirror is embedded in the silicon substrate positioned at the bottom part of the SOI substrate and is positioned below the oblique incidence grating coupler and the
oxide burying layer.