The terms "uniaxial" and "biaxial" come from the optical properties of materials in these states, which are the same as those of a uniaxial crystal
or a biaxial crystal.
As can be seen from Figure 7(a), [n.sub.e] is always larger than [n.sub.0], which means LGN is a positive uniaxial crystal
. A large birefringence [DELTA]n ~ 0.03 is favorable for phase-matching condition.
When there is no applied electric field, the LC molecules are similar to the uniaxial crystal
. The direction of Z axis is consistent with the direction of LC molecular alignment as shown in Figure 1.
Propagation of Lorentz-Gauss beams in free space , in uniaxial crystals orthogonal to the optical axis , and through an apertured fractional Fourier transformation optical system  has also been examined, respectively.
Analytical expressions for the three components of the nonparaxial propagation of a Lorentz-Gauss vortex beam in uniaxial crystals orthogonal to the optical axis have been derived, and the intensity and the phase distributions of the three components have been shown by numerical examples .
Cai, "Paraxial propagation of Lorentz and Lorentz-Gauss beams in uniaxial crystals orthogonal to the optical axis," J.
We have utilized this property of the Comits apparatus to characterize the anisotropic dielectric properties of uniaxial crystals.
Halbout, "Dielectric Properties of Uniaxial Crystals Measured with Optoelectronically Generated Microwave Transient Radiation," submitted for publication.
Te is a kind of positive uniaxial crystals
with principal-refractive indices [n.sub.e] = 6.2 and [n.sub.o] = 4.8.