Doughnut shaped emission from vertical organic nanowire coupled to thin plasmonic film

TL;DR

This paper demonstrates how a hybrid organic-plasmonic nanowire system produces doughnut-shaped emission patterns, potentially useful for nanoscale photon sources carrying orbital angular momentum.

Contribution

It introduces a novel hybrid organic-plasmonic platform that enables engineering of far-field radiation with doughnut-shaped emission patterns from vertical nanowires.

Findings

Doughnut-shaped emission observed in photoluminescence and scattering.

Angular distribution studied via Fourier plane microscopy.

Potential for designing nanoscale photon sources with orbital angular momentum.

Abstract

Vertical nanowires facilitate an innovative mechanism to channel the optical field in the orthogonal direction and act as a nanoscale light source. Subwavelength, vertically oriented nanowire platforms, both of plasmonic and semiconducting variety can facilitate interesting far field emission profiles and potentially carry orbital angular momentum states. Motivated by these prospects, in this letter, we show how a hybrid plasmonic - organic platform can be harnessed to engineer far field radiation. The system that we have employed is an organic nanowire made of diaminoanthroquinone grown on a plasmonic gold film. We experimentally and numerically studied angular distribution of surface plasmon polariton mediated emission from a single, vertical organic nanowire by utilising evanescent excitation and Fourier plane microscopy. Photoluminescence and elastic scattering from single nanowire was analysed individually in terms of in plane momentum states of the outcoupled photons. We found that the emission is doughnut shaped in both photoluminescence and elastic scattering regimes. We anticipate that the discussed results can be relevant in designing efficient, polariton-mediated nanoscale photon sources which can carry orbital angular momentum states.