Waveguide regime

We have seen by Eqs. [38] and [39] that the normal waves are linearly polarized in the local frame of reference for 0. As the local frame rotates d = 2ttzIP), so do the polarization vectors of the normal waves. This is the waveguide regime discussed by de Gennes and is also the regime in which twisted nematic field-effect devices operate (values typical of such devices are P 50 Aim, 1.65 and X 0.5 A m, leading to a value of X 0.006). 

In papers , unsteady-state regime arising upon propagation of the stationary fundamental mode from linear to nonlinear section of a single-mode step-index waveguide was studied via numerical modeling. It was shown that the stationary solution to the paraxial nonlinear wave equation (2.9) at some distance from the end of a nonlinear waveguide has the form of a transversely stable distribution ( nonlinear mode ) dependent on the field intensity, with a width smaller than that of the initial linear distribution. 

Figure 9. Unsteady-state regime in nonlinear waveguide of the structure A, or=1.8 m,P = l.

Thus, in the quasi-static approximation, the length of the unsteady-state regime in the core of the nonlinear waveguide is finite, as in the case of the stationary light beam propagation (see Fig. 10, 11). 

Power losses resulting from the SS effect are observed at the earliest stages of the unsteady-state regime in the nonlinear waveguide of the junction (Fig.28). The losses grow significantly beginning at some distance... 

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