Creating focused plasmons by noncollinear phasematching on functional gratings.

We report on the concept, generation, and first observations of focused surface plasmons on shaped gratings. The grating patterns are designed to realize focusing and directing through noncollinear phasematching. The plasmons are generated on patterned gold surfaces, and the plasmon propagation is observed using phase-sensitive photon scanning tunneling microscopy (PSTM) to extract the propagation pattern, direction, and wavelength.