Optical nanoantennas provide a rich control over light at nanoscale to achieve high field enhancement and localization with a large absorption cross-sections. Considering the need for these virtues in broad range of fields the possible applications of these nanoantennas span into the fields of spectroscopy, photovoltaics, single photon sources, biological sensing.

This seminar discusses the work mainly focused on characterizing and manipulating optical antenna to detect single molecule fluorescence signal at high concentration of micromolar regime. At such high concentration, we need to get the detection volume reduced at least three orders of magnitude beyond diffraction limits. Also, the fluorescence signal enhancement is needed to have a single molecule stand out from the background noisy signal.

The results from this work demonstrates the potential of optical antennas, fabricated by top-down ("antenna-in-box” platform) and bottom-up approach (colloidal synthesis of antennas using gold nanoparticles), to confine light and detect single molecule fluorescence at biologically relevant high concentrations.