High-Bandwidth Silicon Traveling-Wave Modulator Using Distributed Micro-Capacitors

We introduce a bandwidth enhancement technique for traveling-wave Mach-Zehnder modulators (TW-MZM). This approach reduces the microwave attenuation caused by the loaded PN junction capacitance. We achieved a bandwidth of 61 GHz for a 4-mm long silicon modulator, significantly greater than the 45 GHz bandwidth of a conventional design, while maintaining a comparable V
$_\pi$
. Conducted simulations and circuit analysis demonstrated the efficacy of the proposed approach. We also compared the performance of our solution with the reference modulator experimentally in transmission tests at various baud rates. The proposed micro-capacitor-enhanced TW-MZM has a lower bit error rate and can reach up to 120 Gbaud while respecting the bit error rate threshold for forward error correction with a 7% overhead.