Dark nematicons.

@article{Piccardi2011DarkN,
  title={Dark nematicons.},
  author={Armando Piccardi and Alessandro Alberucci and Nelson V. Tabiryan and Gaetano Assanto},
  journal={Optics letters},
  year={2011},
  volume={36 8},
  pages={1356-8}
}
We experimentally demonstrate and model dark spatial solitons in azo-doped liquid crystals, in the presence of saturation and nonlocality of the effective nonlinearity due to changes in molecular order. The guiding properties of dark solitons are probed with a weak input of different wavelength.