Fig. 1. Simulation result of light intensity distribution in directional coupler

Fig. 2. Schematic diagram of the electro-optical modulator

Fig. 3. (a) Diagram of energy transmissivity varies with radius; (b) effect map of non-optimized radius; (c) effect map after radius optimization

Fig. 4. (a) Light intensity distribution of the upper and lower arms of the waveguides varies with the length of directional coupler; (b) minimum coupling length varies with its gap; (c) light splitting effect of directional coupler

Fig. 5. (a) Diagram of cross-section; (b) optical modes; (c) Ex component of electric field;(d) Dx component of electric displacement

Fig. 6. Modulation parameters varies with the voltage