Demonstration and Characterization of High-Speed Silicon Depletion-Mode Mach-Zehnder Modulators

High-speed silicon depletion-mode Mach-Zehnder modulators are demonstrated and characterized in this paper. Based on the structural dimensions and material parameters, transmission-line parameters and frequency response performances of the modulators are calculated and predicted by a proposed distributed circuit model. Parasitic coupled-slotline mode excited by the modulator is analyzed and suppressed by gold-wire bridges. Using a spectrum analysis method, the effect of this modification on the modulated optical signal is simulated. Over a broad frequency range from 10 MHz to 40 GHz, silicon depletion-mode Mach-Zehnder modulators with flat electro-optic modulation responses and broad bandwidths have been experimentally demonstrated.