Counterpropagating dipole beams in nematic liquid crystals

We investigate the behavior of counterpropagating optical beam structures in nematic liquid crystals. We restrict our attention to the dipole-dipole beam arrangements. A time-dependent model for the beam propagation and the director reorientation in nematic liquid crystals is numerically treated in three spatial dimensions and time. Stable dipole beams are observed in a very narrow threshold region of control parameters. Below this region the beams diffract, above the region spatiotemporal instabilities are observed, as the input intensity is increased and also as the distance between the dipole partners is decreased. A transverse beam displacement of counterpropagating dipole beams is also found. The difference between the in-phase and out-of-phase components of the dipole is significant, but only for a smaller distance between the dipole partners.