A Coplanar-Waveguide-Based Silicon Mach-Zehnder Modulator using a Meandering Optical Waveguide and Alternating-side PN junction loading

We demonstrate a silicon Mach-Zehnder modulator with a coplanar waveguide transmission-line electrode structure using a meandering optical waveguide and alternating-side PN junction loading of the electrodes, which helps suppress the signal distortion caused by the parasitic slot-line mode and improves the electro-optical bandwidth. The silicon MZM exhibits a V-pi of 4.5 V with an electro-optic 3-dB bandwidth ~20 GHz for a 5 mm-long phase shifter. This achieved V-pi is among the lowest for silicon-only modulators with a bandwidth of more than 20 GHz.