Coplanar waveguide electrode designs for high-speed polymer electrooptic modulator

Electrooptic polymer waveguide modulators have demonstrated excellent characterizations including high-speed (with a bandwidth up to 100 GHz) and lower drive voltages [1]. A key factor to achieve efficient high-speed modulation in polymer devices is to design wide bandwidth electrodes. Theoretical simulations to optimize microstrip line (MSL) electrode design for high-speed polymer modulators have recently been reported [2]. To further optimize electrode design, we have investigated coplanar waveguide (CPW) electrodes, which has been the only electrode structure for high-speed optical modulators based on inorganic crystals. It is found that bandwidth of the coplanar waveguide (CPW) electrode is significantly higher than that of the microstrip line (MSL), which are most commonly employed for high-speed optical polymer modulators. More importantly, electric fields applied on two arms of optical Mach-Zehnder Interferometer (MZI) are naturally opposite, therefore, no posh-pull poling is needed in the processing. Furthermore, CPW electrodes also possess advantages including coplanar structures, which eases packaging process, capability of multilevel stacking and easy connections to the external coaxial lines.