Multi-beam excitation and interference interaction of surface plasmon polaritons

The work is devoted to study interference effects in systems with several coherently excited surface plasmon polariton (SPP) beams. Two-beam excitation is experimentally realized using a Michelson-interferometer, allowing to control the intensity and the polarization state in both beams independently. The initial laser beam is divided into two replicas which are focused by a single microscope objective and irradiate a gold surface at different positions. SPPs are excited by localized scattering of the laser light on laser-fabricated nanostructures. The surface nanostructures are produced by two-photon polymerization of spin-coatable epoxy-based resist on a metal covered glass slide. Moreover, the obtained dielectric structures can be combined with spherical gold nanoparticles of arbitrary size produced by the method of laser-induced transfer. The particles are considered as additional SPP scattering centres and can be used for manipulation of the SPP intensity. SPP interference and scattering effects are investigated by leakage radiation microscopy (LRM).