We present a new design of a miniaturized modulator on a silicon chip. The modulation principle is based upon the plasma dispersion effect in which free electrons affect the real and the imaginary part of the refractive index. The novelty of the modulation configuration is related to its periodically patterned electrodes due to which the applied voltage generates axially periodic change in index of refraction. This results with the generation of an effective Bragg filter. Such filter allows having shorter device with the same extinction ratio or having a device with the same length but with improved modulation contrast.