Two-photon polymerization and applications in plasmonics

Renewed and growing interest in the field of surface plasmon polaritons (SPPs) comes from a rapid advance of nanostructuring technologies. The desired nanostructures are usually fabricated by electron- or ion-beam lithography. An alternative approach is the application of two-photon polymerization (2PP) or nonlinear lithography. Both these technologies are based on nonlinear absorption of near-infrared femtosecond laser pulses. With 2PP, the fabrication of three-dimensional micro-objects and photonic crystals with a resolution down to 100 nm is possible. In this contribution, we study applications of advanced femtosecond laser technologies for the fabrication of SPP structures. We demonstrate that resulting structures can be used for excitation, guiding, and manipulation of SPPs on a subwavelength scale. Characterization of these structures is performed by detection of the plasmon leakage radiation (LR). 2PP allows the fabrication of dielectric waveguides, splitters, and couplers directly on metal surfaces. The fabricated dielectric structures are also very efficient for the excitation of SPPs. Using these structures, excitation and focusing of the resulting plasmon field can be achieved.