  The electron transmission between monolayer and bilayer graphene is
theoretically studied for zigzag and armchair boundaries within an
effective-mass scheme. Due to the presence of an evanescent wave in the bilayer
graphene, traveling modes are well connected to each other. The transmission
through the boundary is strongly dependent on the incident angle and the
dependence is opposite between the K and K' points, leading to valley
polarization of transmitted wave.
