Directional exciton-polariton photoluminescence emission from terminals of a microsphere-coupled organic waveguide

Abstract

We report on angle-resolved, exciton-polariton photoluminescence measurements from asymmetric terminals of a microsphere-coupled organic waveguide (MOW). The MOW architecture consisted of a SiO2 microsphere coupled with a diaminoanthroquinone mesowire, self-assembled on a glass substrate. The angle-resolved emission measurements were performed using spatially filtered Fourier-plane optical imaging method. The light emanating from the sphere-terminus had two regions of angular emission in the Fourier-plane, of which one had azimuthal angular spread as small as 10°. The emission from wire terminus was uni-directional in nature, with some light emitted beyond the critical angle of glass-air interface. Our results highlight unique directional emission characteristics of a hybrid organic waveguide geometry and may have implications on single-element, exciton-polariton based light-emitting devices and lasers. This research work was partially funded by DST-Nanomission Grant (SR/NM/NS-1141/2012(G)) and DST Nanoscience Unit Grant (SR/NM/NS-42/2009), India. R.C. wishes to acknowledge financial support from KVPY fellowship.