Two-path self-interference in PTCDA active waveguides maps the dispersion and refraction of a single waveguide mode

Abstract

Bound waveguide modes propagating along nanostructures are of high importance since they offer low-loss energy-/signal-transport for future integrated photonic circuits. Particularly, the dispersion relation of these modes is of fundamental interest for the understanding of light propagation in waveguides as well as of light-matter interactions. However, for a bound waveguide mode, it is experimentally very challenging to determine the dispersion relation. Here, we apply a two-path interference experiment on microstructured single-mode active organic waveguides that is able to directly visualize the dispersion of the waveguide mode in energy-momentum space. Furthermore, we are able to observe the refraction of this mode at a structure edge by detecting directional interference patterns in the back-focal plane.