Linearity Measurement and Pulse Amplitude Modulation in a Silicon Single-Drive Push-Pull Mach-Zehnder Modulator

We characterize the modulation linearity of a silicon Mach-Zehnder modulator with a single-drive push-pull configuration. The 3-dB electro-optic bandwidths of the modulator are 15 and 32 GHz at 0 and 6 V reverse biases, respectively. The best spurious-free dynamic ranges (SFDRs) for the second-order harmonic distortion and the third-order intermodulation distortion are measured to be 97.7 dB.Hz(2/3) and 85.9 dB.Hz(1/2). The experimental measurement demonstrates that such a drive scheme can effectively reduce the modulation nonlinearity, especially the second harmonic distortion. Multi-level pulse amplitude modulation (PAM) is achieved using this high-linearity modulator with PAM-2,3,4,5 at a symbol rate of 40 Gbaud/s and PAM-8 at a symbol rate of 25 Gbaud/s.