Polyfluorene nanowire active waveguides as sub-wavelength polarized light sources

Poly(9,9-dioctylfluorene) conjugated polymer nanowire active waveguides were fabricated by melt-assisted wetting of porous anodic alumina templates. Selected-area electron diffraction studies indicated that the wires were semi-crystalline with a radial orientation of the polymer molecules. Under ultraviolet excitation, the characteristic blue light emission of the polymer was strongly confined within the wires, propagating towards and out-coupling at the nanowire tips. Single wire polarization-resolved photoluminescence data indicated that the nanowire tips essentially acted as sub-wavelength polarized light sources. Detailed optical measurements made on single wires in vacuum and in a polymer host confirmed that the measured emission anisotropy was not an environment-related artefact but was due to radial packing of the polymer molecules within the wires.