  We study the chirality of periodically poled MgO-doped lithium niobate
(MgO:PPLN) by electro-optic (EO) effect. It shows that optical propagation is
reciprocal in MgO:PPLN when quasi-phase-matching (QPM) condition is satisfied,
which is similar to natural optical active material like quartz. The specific
rotation of MgO:PPLN by EO effect is shown to be proportional to the transverse
electric field, making large polarization rotation in optical active material
with small size possible. We also demonstrate that the chirality of MgO:PPLN
can be controlled by external electric field.
