Efficient excitation and control of arbitrary surface plasmon polariton beams using one-dimensional metallic gratings

We derive a general approach for efficient excitation and control of arbitrarily shaped surface plasmon polariton waves, using one-dimensional metallic gratings by tailoring the exciting beam. We present a complete and rigorous theory that relates the electromagnetic fields of the free-space beam impinging on the grating to the resulting surface plasmon. We deduce an optimal grating and efficient polarization schemes which facilitate the excitation of surface plasmons propagating at angles up to almost 90 deg with respect to the grating's axis with negligible polarization losses. The theoretical predictions are verified both numerically and experimentally by exciting two-dimensional surface plasmons through one-dimensional metallic gratings. We show that this method can be readily applied for generating arbitrary plasmonic wave fronts, and the general design formalism is given. Finally, we show how the developed design rules can be applied for the excitation of optically controlled surface plasmon hot spots.