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Efficient low-loss InGaAsP/Si hybrid MOS optical modulator

Abstract

An optical modulator integrated on silicon is a key enabler for high-performance optical interconnects1,2,3,4,5,6. However, Si-based optical modulators suffer from low phase-modulation efficiency owing to the weak plasma dispersion effect in Si, which also results in large optical loss. Therefore, it is essential to find a novel modulation scheme for Si photonics. Here, we demonstrate an InGaAsP/Si hybrid metal-oxide–semiconductor (MOS) optical modulator formed by direct wafer bonding7,8. Electron accumulation at the InGaAsP MOS interface enables the utilization of the electron-induced refractive index change in InGaAsP, which is significantly greater than that in Si (refs 9,10). The presented modulator exhibits a phase-modulation efficiency of 0.047 Vcm and low optical attenuation of 0.23 dB at π phase shift at 1.55 μm wavelength, which are approximately 5 times higher and 10 times lower than Si MOS optical modulators11,12,13,14,15,16,17, respectively. This approach provides a new, high-performance phase-modulation scheme for Si photonics.

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Figure 1: Schematics and images of an InGaAsP/Si hybrid MOS optical modulator.
Figure 2: Numerical analysis of an InGaAsP/Si hybrid MOS optical modulator.
Figure 3: Measurement of an InGaAsP/Si hybrid MOS optical modulator.
Figure 4: Benchmarks of the modulation efficiency and loss for an InGaAsP/Si hybrid MOS optical modulator.
Figure 5: Benchmarks of the modulation bandwidth for an InGaAsP/Si hybrid MOS optical modulator.

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Acknowledgements

This work was supported in part by the New Energy and Industrial Technology Development Organization (NEDO) and the Japan Society for the Promotion of Science (JSPS) KAKENHI grant number JP26709022. The authors would like to thank O. Ichikawa, M. Yokoyama, T. Yamamoto and H. Yamada in Sumitomo Chemical Corporation for their collaboration. J.-H.H. and F.B. would also like to thank JSPS for a research fellowship.

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J.-H.H. contributed to the idea, simulation, fabrication, measurement and manuscript preparation. F.B. contributed to the simulation and manuscript preparation. J.F. and S. Takahashi contributed to the measurement of the dynamic characteristics. S.Takagi contributed to the discussion and provided high-level project supervision. M.T. contributed to the idea, discussion, manuscript revision, and provided high-level project supervision.

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Correspondence to Jae-Hoon Han or Mitsuru Takenaka.

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The authors declare no competing financial interests.

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Han, JH., Boeuf, F., Fujikata, J. et al. Efficient low-loss InGaAsP/Si hybrid MOS optical modulator. Nature Photon 11, 486–490 (2017). https://doi.org/10.1038/nphoton.2017.122

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