This paper presents study of a new electrooptical effect in an optically active nematic chiral structure beyond Mauguin's region. The absence of oscillations in the transmission-voltage curve, reduced requirements for orienting surfaces, and, functioning independent of the direction of polarization, all provide the proof of this effect. The extent of the relationship between wavelength, helical path and optical anisotropy of the nematic matrix is analyzed. Dispersion properties and applications to white-light modulation are presented.