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(a) Top view and (b) cross-section (in xz) at a generic z of the cell. The director at rest is parallel to , and the electrodes are such that the dominant component of is at an angle with is the comb periodicity. (c) Sketch of the interaction between the electric field and themolecules of DFLC. (d) Walk-off versus rms value of the applied bias for positive (dashed line with squares, ) and negative DFLC anisotropy (dashed line with circles, ).
Acquired images of nematicon steering versus frequency f. (a) Unperturbed case V = 0 V. (b) For f = 1 kHz and V = 6 V, the dielectric anisotropy is positive, thus the torque pushes the director towards the applied field ( ) and the resulting soliton walk-off is . (c) For f = 15 kHz and V = 6 V, the beam propagates along z, as in the case V = 0 V; hence the nonlinearity vanishes and the beam diffracts as and the torque is negligible. (d) For f = 50 kHz and V = 6 V, the negative electric torque saturates, thus and .
Walk-off versus frequency for three voltage amplitudes [points are the experimental data, whereas solid lines are the theoretical computation from Eqs. (1) and (2) , with the electrical anisotropy taken from Ref. 38 ]. The curves cross at , i.e., the crossover value at which the dielectric anisotropy is zero and no torque acts on the molecules. Inset: zoom-in around ; here, the error bars are not shown.
Average beam waist w normalized to the input value versus f. The beam is self-confined at every frequency except around f = 15kHz, corresponding to . The input power is 15 mW and the bias is V = 6 V.
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