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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 capacity1,2,3,4. 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 (VπL), 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 VπL 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.

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Figure 1: Device design.
Figure 2: Calculated performance.
Figure 3: Measured static characteristics.
Figure 4: Measured dynamic characteristics.


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Authors and Affiliations



T.H. calculated, designed, fabricated and measured the devices, and prepared the manuscript. T.A. contributed to making the device layout and assisted in measuring the device. K.H. contributed to fabricating the III–V semiconductor layer. K.T. performed the III–V semiconductor wafer bonding onto Si. T.F. performed the epitaxial growth of the III–V semiconductor layer. T.T. contributed to fabricating the Si layer. T.K. assisted in the calculations. H.F. contributed to analysing the measurement results and supervised the project. S.M. discussed the fabrication process, contributed to analysing the measurement results, supervised the project and assisted in revising the manuscript.

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Correspondence to Tatsurou Hiraki.

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The authors declare no competing financial interests.

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Hiraki, T., Aihara, T., Hasebe, K. et al. Heterogeneously integrated III–V/Si MOS capacitor Mach–Zehnder modulator. Nature Photon 11, 482–485 (2017).

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