High-speed silicon optical modulator with a single-drive push-pull scheme

We have demonstrated a silicon traveling wave Mach-Zehnder modulator adopting the single-drive push-pull scheme. The traveling wave electrode is made of coplanar stripline structure. Several key parameters have been optimized to get a high-speed modulator. It is shown that using the coplanar stripline electrode, group velocity matching and impedance matching are achieved by careful design. After optimization, the VπL of the modulator is calculated to be 2.23 V·cm with the phase shifter length of 4.2 mm. The insertion loss of the modulator excluding the grating couplers loss is 3.4 dB. The 3 dB electro-optic bandwidth of the modulator is simulated to be 32 GHz at 0 V reverse bias. A modulation speed of 70 Gbps under the driving voltage of 1 Vpp is realized with an extinction ratio of 4.9 dB. A higher data transmission capability can be get when high modulation formats such as PAM-4, together with digital signal processing is implemented. Such high-speed silicon modulator can be utilized for next generation communication networks.