title: Plasmon-controlled excitonic emission from vertically-tapered organic nanowires.
abstract: Organic molecular nanophotonics has emerged as an important avenue to harness molecular aggregation and crystallization on various functional platforms to obtain nano-optical devices. To this end, there is growing interest to combine organic molecular nanostructures with plasmonic surfaces and interfaces. Motivated by this, herein we introduce a unique geometry: vertically-tapered organic nanowires grown on a plasmonic thin film. A polarization-sensitive plasmon-polariton on a gold thin-film was harnessed to control the exciton-polariton propagation and subsequent photoluminescence from an organic nanowire made of diaminoanthraquinone (DAAQ) molecules. We show that the exciton-polariton emission from individual DAAQ nanowires can be modulated up to a factor of 6 by varying the excitation polarization state of surface plasmons. Our observations were corroborated with full-wave three-dimensional finite-difference time-domain calculations performed on vertically-tapered nanowire geometry. Our work introduces a new optical platform to study coupling between propagating plasmons and propagating excitons, and may have implications in emerging fields such as hybrid-polariton based light emitting devices and vertical-cavity nano-optomechanics.
authors.affiliation: Photonics and Optical Nanoscopy Laboratory, Department of Physics and Center for Energy Science, Indian Institute of Science Education and Research, Pune 411008, India. pavan@iiserpune.ac.in.
authors.forename: Rohit
authors.initials: R
authors.lastname: Chikkaraddy
authors.forename: Partha Pratim
authors.initials: PP
authors.lastname: Patra
authors.forename: Ravi P N
authors.initials: RP
authors.lastname: Tripathi
authors.forename: Arindam
authors.initials: A
authors.lastname: Dasgupta
authors.forename: G V Pavan
authors.initials: GV
authors.lastname: Kumar