Nematicons in liquid crystals with negative dielectric anisotropy
  We report a theoretical and experimental work on the nematicon in the planar cell containing the nematic liquid crystal with negative dielectric anisotropy, aligned homeotropically in the presence of an externally applied voltage. The formation of the soliton is resulted from the balance between the linear difrraction and the nonlocal nonlinearity due to molecular reorientation. 
Jing Wang, Junzhu Chen, Jinlong Liu, Yiheng Li, Qi Guo, Wei Hu, Dayu   Li, Yonggang Liu, and Li Xuan
physics.optics