Heterogeneously integrated III-V/Si MOS capacitor Mach-Zehnder modulator

Demand for more transmission capacity in data centres is increasing due to the continuous growth of Internet traffic. The introduction of external modulators into datacom networks is essential with advanced modulation formats. However, the large footprint of silicon photonics Mach-Zehnder (MZ) modulators will limit further increases in transmission capacity. To overcome this, we introduce III-V compound semiconductors because the large electron-induced refractive-index change, high electron mobility and low carrier-plasma absorption are beneficial for overcoming the trade-offs among the voltage-length product (V π L), operation speed and insertion loss of Si MZ modulators. Here, we demonstrate an MZ modulator with a 250-μm-long InGaAsP/Si metal-oxide-semiconductor (MOS) capacitor phase-shifter and obtain a V π L of 0.09...Vcm in accumulation mode, an insertion loss of ∼1.0...dB, a cutoff frequency of ∼2.2...GHz in depletion mode and a 32-Gbit...s -1 modulation with signal pre-emphasis. These results are promising for fabricating high-capacity large-scale photonic integrated circuits with low power consumption.