Light-modulated electron retroreflection and Klein tunneling in a graphene-based n-p-n junction

We investigate the electron retroreflection and the Klein tunneling across a graphene-based n-p-n junction irradiated by linearly polarized off-resonant light with the polarization along the x direction. The linearly polarized off-resonant light modifies the band structure of graphene, which leads to the anisotropy of band structure. By adjusting the linearly polarized light and the direction of n-p-n junction simultaneously, the electron retroreflection appears and the anomalous Klein tunneling, the perfect transmission at a nonzero incident angle regardless of the width and height of potential barrier, happens, which arises from the fact that the light-induced anisotropic band structure changes the relation of wavevector and velocity of electron. Our finding provides an alternative and flexible method to modulate electron retroreflection and Klein tunneling.