Nematicon-driven injection of amplified spontaneous emission into an optical fiber

We investigate experimentally the interaction between
amplified spontaneous emission (ASE) and a soliton,
which are both generated in a dye-doped nematic liquid
crystal (LC) cell. A light beam is injected through
an optical fiber slid into the cell to form a soliton beam.
ASE is then automatically collected by this self-induced
waveguide and efficiently coupled into the same optical
fiber, in the backward direction. We demonstrate
that the presence of the soliton improves the ASE collection
by one order of magnitude. We also show that
the ASE is highly polarized in the plane of the LC cell,
and that the ASE spectrum depends on the pump stripe
orientation with respect to the LC director. The origin
of the spectral anisotropy of the gain curves is determined
with the help of femtosecond pump-probe spectroscopy.