Multifunctional Plasmonic Film for Recording Near-Field Optical Intensity

We
demonstrate the plasmonic equivalent of photographic film for
recording optical intensity in the near field. The plasmonic structure
is based on gold bowtie nanoantenna arrays fabricated on SiO2 pillars. We show that it can be employed for direct laser writing
of image data or recording the polarization structure of optical vector
beams. Scanning electron micrographs reveal a careful sculpting of
the radius of curvature and height of the triangles composing the
illuminated nanoantennas, as a result of plasmonic heating, that permits
spatial tunability of the resonance response of the nanoantennas without
sacrificing their geometric integrity. In contrast to other memory-dedicated
approaches using Au nanorods embedded in a matrix medium, plasmonic
film can be used in multiple application domains. To demonstrate this
functionality, we utilize the structures as plasmonic optical tweezers
and show sequestering of SiO2 microparticles into optically
written channels formed between exposed sections of the film. The
plasmonic film offers interesting possibilities for photonic applications
including optofluidic channels “without walls,” in situ
tailorable biochemical sensing assays, and near-field particle manipulation
and sorting.