Polarization-controllably launching localized cosine-Gauss beam with spatially varied metallic nano-apertures.

Two properly designed columns of orthogonally tilted and spatially varied nano-apertures have been demonstrated to achieve polarization-controlled launching of the localized cosine-Gauss beam, which is a kind of highly localized surface plasmonic wave without diffraction. According to the experimental results, the generated unidirectional propagating plasmonic beam could propagate with a non-diffracting length of up to 57µm as well as the extinction ratio of more than 150. We believe that our proposed device would play an important role in highly compact photonic circuit on-chip with plasmonic wave.