Adiabatic propagation in nematic liquid crystals with competing nonlinearities

We theoretically investigate the influence of the variation of the nonlocal degree of the molecular orientation effect sigma 1 and the nonlocal degree of the thermal effect sigma 2 on beam propagation in nonlocal media with competing nonlinearities. According to the model proposed by JUNG P S, we find that variations in sigma 1 and sigma 2 have completely different effects on beam propagation in the medium. When sigma 1 increases, the beam tends to broaden, whereas when sigma 2 increases, the beam tends to compress. Numerical calculations, conducted using the split-step Fourier method, show that changes in sigma 2 have a smaller effect on propagation compared to sigma 1. Adiabatic propagation of the beam in nematic liquid crystals can be achieved if sigma 1 changes gradually, but not if sigma 1 changes abruptly. In contrast, adiabatic propagation can be realized with sigma 2 whether it changes abruptly or gradually. The variational results are well confirmed by numerical simulations.