  It is shown that the direct Fourier synthesization of light beams allows one
to create polarity-asymmetric waves, which are able, in the process of
nonlinear interaction with a medium, to break its inversion symmetry. As a
result, these "polar" waves may show the effect of optical rectification in
nonlinear centrosymmetric media by generating light-induced dc electric
polarization. At the same time, the waves of this type, due to their unusual
symmetry properties, can be used for detecting the direction and sign of a dc
electric field applied to the medium. The prospects of application of polar
waves to data recording and processing are discussed.
