Emission characteristics of organic meso/nanowires coupled with dielectric and plasmonic structures

Abstract

Is it possible to effectively transport light through the channels smaller than the wavelength of light? This is the question that we are trying to answer in this thesis, apparently question is at the heart of nanophotonics. Here we address this issue by harvesting organic meso/nanowires to propagate light from one point to another. In the context of building nanophotonic circuits it is very important to have control over the characteristics of light such as modulation of amplitude, phase and polarization states of light. This is possible via formation of precise junctions and interconnections. Motivated by this we have interfaced organic mesowires with different substrates such as optical cavities and plasmonic films. Nanophotonic systems such as optical cavities and waveguides have emerged as high sensitive bio-sensors and effective medium for signal transportation, respectively. But fabricating both optical cavities and waveguides in a single architecture is of great challenge and has importance in doing remote detection studies, which has relevance in monitoring photo-physics of light sensitive systems. We interfaced organic mesowires with spherical high-Q microcavity for above mentioned purpose. Further we excite and detect microcavity modes remotely through organic mesowire as a channel of signal transporter. We also observed mode mixing and splitting property of spherical mocrocavity due to broken azimuthal symmetry. It is very exciting to observe transition in radiation properties from dipolar in simple organic mesowire compared to quadruple in organic mesowire coupled with spherical microcavity. What are the polarization states of light emitted through the nanowire? How to convert linearly polarized states of light into elliptically polarized light at nanoscale? Addressing these questions has importance in probing chiral molecules at single copy limit and building optical-magnetic recording devices. We have ventured these new polarized states of light in vertical organic nanowires coupled with plasmonic films. These nanowires are standing perpendicular to the substrate, the emission of light from the tip of these nanowire is analysed. These nanowires are excited through energy transport from plasmons to excitons at junctions of metal film and organic nanowire. The emitted light contains elliptically polarized states of light with relatively high degree of polarization 0.410.03;