Nanophotonics of Organic Molecular Waveguides: Towards Active Optical Antenna

Photons as information and energy carriers, reside at the heart of nano-optics and photonics, and controlling them at sub-wavelength scale has emerged as an outstanding problem in optical physics. An excellent control over optical field at nanoscale has relevance in various scientific domains such as fundamental light-matter interaction, optical spectroscopy, quantum optics, optical communications, and biomedical imaging, etc. In recent years, an important question has emerged in the context of nanophotonics: how to efficiently couple, direct and extract optical energy between optical nanostructures. An effective answer to this question is vital in the context of nanoscale energy transfer processes that are of fundamental importance. In this context, a variety of micro- and nanostructures have been explored in the past few years, however most of the investigations are confined to plasmonic nanostructures. There are few concerns (such as heating and propagation loss, CMOS compatibility, efficiency and flexibility etc.) associated with conventional plasmonic materials, which are regarded as deterrents in realizing various nanophotonic applications. Therefore, it is vital to explore alternative candidates to eliminate the bottleneck for practical realization of nanophotonic devices. 

To address many of these issues, we have experimentally investigated one dimensional organic molecular meso- and nanostructures that facilitate Frenkel exciton-polaritons. Firstly, we studied how organic nanostructures act as a directional optical antenna in different spectral regimes. Secondly, we investigated the influence on directional emission due to physical coupling with microsphere resonator architectures. Lastly, we have explored coupling between a single organic nanowire with unstructured plasmonic platform and demonstrated the impact of near-field coupling on radiative channelling of exciton-polaritons through plasmonic substrate