Temperature control of nematicon trajectories

Using modulation theory, we develop a simple $\mathrm{[}(2+1)$-dimensional] model to describe the synergy between the thermo-optical and reorientational responses of nematic liquid crystals to light beams to describe the routing of spatial optical solitary waves (nematicons) in such a uniaxial environment. Introducing several approximations based on the nonlocal physics of the material, we are able to predict the trajectories of nematicons and their angular steering with temperature, accounting for the energy exchange between the input beam and the medium through one-photon absorption. The theoretical results are then compared to experimental data from previous studies, showing excellent agreement.

Figure 1

Sketch of a thick planar cell showing input wave vector $\mathbf{k}$ of the beam, extraordinary-wave walkoff $\delta ={tan}^{-1}\mathrm{\Delta }$ and preset orientation of NLC molecules.

Figure 2

Comparison between the experimental data for (a) $n_{\parallel }$ and (b) $n_{\perp }$ as a function of temperature in E7 [35] and the interpolating polynomials (30) and (31). Experimental data: squares; interpolating polynomials: solid lines.

Figure 3

Comparison between the experimental data (symbols) of Ref. [35] for the beam walkoff angle and the results of the model (28) (color lines), at various temperatures between ${22}^{\circ }$ and ${55}^{\circ }$. The experimental results were averaged over various input powers at $1.064\mu \text{m}$. The error bars resulted from transverse fluctuations of the beam, as well as the limited accuracy of the setup. Color lines are (28) for beam powers 2, 4, 5, 7.5, 15, and $20\text{mW}$ (from top to bottom), respectively.