Polarization-insensitive electro-optical modulator based on polymer-filled silicon cross-slot waveguide

A silicon cross-slot waveguide filled with electro-optic polymer is proposed to release the polarization-dependent issue of the electro-optic modulator. There are two slots in both the horizontal direction and vertical direction, so this waveguide structure can confine both the TE and TM modes. The four silicon regions can be lightly doped as the electrodes. There is slanted electric field in the slot region when the voltages are applied on the electrodes. The electric field component act at principal optical axis whose electric-optic (EO) coefficient is r33 or r13 can be adjusted by changing the voltages on the four electrodes. With optimal voltages, the effective refractive index of the TE and TM modes can be changed equally. The Mach-Zehnder modulator based on cross-slot waveguide can achieve polarization-insensitive.