  We report on a very first experimental observation of a new curved plasmonic
beam, a plasmonic hook (PH), for surface plasmon-polariton (SPP) waves. We
demonstrate that the SPP PH effect could be realized within a trapezoidal
dielectric microstructure with the relative ease of fabrication compared to the
generation of the Airy SPP waves which require complex techniques to compensate
the wave vectors mismatch. Using numerical analysis, we predicted the PH
phenomenon, optimized the microstructure and then confirmed the SPP PH
existence via amplitude and phase-resolved scattering scanning near-field
optical microscopy at the telecom wavelengths of 1530-1570 nm. The experimental
results are in reasonable agreement with our predictions. Importantly, the SPP
PH demonstrates the smallest radius of curvature ever recorded for SPP waves
compared to that for the Airy-family plasmonic beams providing many useful
applications spreading from nanoparticles manipulation toward bio-sensing
within a nanoscale.
