Compact Silicon Electro-Optical Modulator Using Hybrid ITO Tri-Coupled Waveguides

Silicon based electro-optical modulators are essential for optical communication systems. In this paper, we present a silicon electro-optical modulator, which is based on tri-coupled waveguides. Two of these waveguides are silicon-on-insulator slot waveguides separated by a hybrid Indium Tin Oxide intermediate waveguide. The silicon-on-insulator slot waveguides reaps the advantages of the high mode confinement. The power-splitting mechanism can be electrically tuned through applying external electric field to the intermediate plasmonic waveguide. The tuning mechanism is designed such that it will both change the coupling conditions and introduces additional intrinsic losses at the telecommunication wavelength (1550 nm). The modulator was optimized by three-dimensional full finite difference time domain electromagnetic simulations. Extinction ratio of 6.14 dB and insertion losses of 0.06 dB are realized at 21 μm modulator length; as well as, extinction ratio of 11.43 dB and insertion losses of 1.65 dB are realized at 34 μm modulator length. The proposed silicon electro-optical modulator can potentially play a key role in the next generation of the onchip electronic-photonic integrated circuits.