  The Pockels effect can increase the effective birefringence of ambichiral,
electro--optic rejection filters made of materials with a $\bar{4}2m$ point
group symmetry, when a dc electric field is applied parallel to the axis of
nonhomogeneity. The reflectances and the transmittances of such an ambichiral
structure for obliquely incident plane waves is solvable through a
boundary-value problem that is formulated using the frequency-domain Maxwell
equations, the constitutive equations that contain the Pockels effect, and
standard algebraic techniques for handling 4x4 matrix ordinary differential
equations. The Bragg resonance peaks, for different
circular-polarized-incidence conditions, blueshift as the angle of incidence
increases. These blueshifts are unaffected by the sign of the dc electric
field.

Optics