The properties of truly confined modes of a 2D hex horizontal photonic crystal slot slab waveguide are analyzed. Then
the dispersion of liner defect waveguide is calculated. In addition, what influence the slots with different height have
over the band structure and the group velocity dispersion of the defect mode waveguide are analyzed. Based on these
studies, an ultra-compact silicon-based Mach-Zehnder amplitude modulator is proposed. For a design with almost
negligible first order chromatic dispersion in an optical bandwidth of 1THz, we predict a modulation bandwidth of
40GHz and a length of about 80µm. This is achieved by infiltrating an electro-optic polymer into a slotted photonic
crystal waveguide, the strong field confinement in slotted waveguides and the slow light interaction enhancements
provided by the photonic crystal waveguide, where group velocity and dispersion may be controlled.