A graphene-based valley filter includes a bottom gate, a bilayer graphene and two top gates. The bilayer graphene is deposited on the bottom gate and includes scattering defects. The top gates are deposited on the bilayer graphene. The top gates define a channel in the bilayer graphene, and the scattering defects are located in the vicinity of the channel. A vertical electric field is formed to open a band gap and produce electronic energy subbands in the channel. A transverse in-plane electric field is formed to produce pseudospin splitting in the subbands of the bilayer graphene. The scattering defects are for producing scattering between two opposite energy valley states of the bilayer graphene, couples subband states of opposite pseudospins and opens a pseudogap at a crossing point of the two subbands. Electrons are passed through the channel to become valley polarized in the bilayer graphene. |