Optical waveguiding in individual nanometer-scale organic fibers

We show by a combination of spectrally resolved fluorescence and atomic force microscopy that individual, single crystalline, needlelike aggregates of hexaphenyl molecules with submicron cross-sectional dimensions act as optical waveguides ("nanofibers") in the blue spectral range. The nanofibers are formed via laser-supported, dipole-assisted self-assembly on single crystalline mica substrates. This method allows us to modify the morphology of individual aggregates as well as their mutual distances and the overall orientation of needle arrays. An analytical theory describes quantitatively the waveguiding behavior. From measurements of the damping of propagating 425-nm light the imaginary part of the dielectric function of individual nanoscaled organic aggregates is determined.