Abstract: A polymer directional coupler (DC) electro-optic switch with push-pull electrodes and rib waveguides is designed based on the conformal transforming method,image method,coupled mode theory,and electro-optic modulation theory.Its structure and principle are described,the design and optimization are performed,and the characteristics are analyzed,including the coupling length,switching voltage,output power,insertion loss,and crosstalk.To realize normal switching function,the fabrication tolerance,wavelength shift,and coupling loss between a single mode fiber (SMF) and the waveguide are discussed.Simulation results show that the coupling length is 3082μm;the push-pull switching voltage is 2.14V;and the insertion loss and crosstalk are less than 1.14 and -30dB,respectively.The proposed analytical technique on waveguides and electrodes is proven to be accurate and computationally efficient when compared with the beam propagation method (BPM) and the experimental results.

Key words: electro-optic switch, push-pull electrodes, coupling length, switching voltage, insertion loss, crosstalk