Propagation loss spectroscopy on single nanowire active waveguides.

A new technique is reported where by combining spatially and spectrally resolved scanning optical microscopy on single nanowire active waveguides, waveguide propagation loss and dispersion can be determined. The waveguide propagation loss spectra have been utilized to obtain insights into the optical absorption spectra of these unique nanostructured materials, which are modified in comparison to bulk materials. The propagation spectra and waveguide dispersion show clear signatures of electronic effects such as exciton-polariton formation. These results show the importance of the polaritonic nature of waveguiding in semiconducting nanoscale optical cavities and provide insights for the integration of semiconductor nanowire waveguides in nanophotonic circuitry.