  Controlling the dispersion and directionality of the emission of nanosources
is one of the major goals of nanophotonics research. This control will allow
the development of highly efficient nanosources even at the single photon
level. One of the ways to achieve this goal is to couple the emission to Bloch
modes of periodic structures. Here, we present the first measurements of the
directional emission from nanowire photonic crystals by using Fourier
microscopy. With this technique we efficiently collect and resolve the
directional emission of nanowires within the numerical aperture of a microscope
objective. The light emission from a heterostructure grown in each nanowire is
governed by the photonic (Bloch) modes of the photonic crystal. We also
demonstrate that the directionality of the emission can be easily controlled by
infiltrating the photonic crystal with a high refractive index liquid. This
work opens new possibilities for the control of the emission of sources in
nanowires.
