Performance assessment of a silicon traveling-wave Mach-Zehnder modulator employing quasi-TM mode propagation

A silicon Mach-Zehnder modulator (MZM) with quasi-TM mode propagation is investigated for non-return-to-zero on-off keying modulation. The quasi-TM PN phase shifter phase-loss characteristics have been determined and shown to exhibit better performance compared to quasi-TE phase shifter with the same waveguide cross-sectional area and device parameters. The phase shifter modulation efficiency is 1.02 V.cm. The MZM transfer characteristics are determined for the dual-arm push-pull driving scheme, and a traveling-wave electrode structure is employed to enhance the device bandwidth. A 3-dB bandwidth of 74 GHz is obtained at 2.5-V reverse bias. The modulator high-speed characteristics are studied for different data rates over single-mode fiber transmission. A 30-km fiber transmission with an open eye at 160 Gbps with 2-V peak-to-peak drive is obtained with an extinction ratio of 2.3 dB and bit-error-rate (BER) of ∼2.77 × 10 - 06. The effect of fiber dispersion on the BER shows dispersion tolerance from 0 to -1.73 ps. nm - 1. km - 1 for 30-km fiber transmission below the hard-decision forward error correction threshold at 100-Gbps operation.