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Femtofarad optoelectronic integration demonstrating energy-saving signal conversion and nonlinear functions


The introduction of photonic technologies into mature electronic circuits is in high demand to accelerate on-chip information networking and even computing. Great difficulty lies in the fact that the optoelectronic coupling at their interfaces requires a substantial charging energy determined by their capacitance. Optoelectronic devices have been too large to reduce the integrated capacitance down to the femtofarad scale. Here we use a photonic-crystal platform to demonstrate the first experimental proof of optoelectronic integration at only 2 fF. This allows us to realize a record-low attojoule-energy electro-optic modulator (an electrical-to-optical or E–O converter) and an amplifier-free photoreceiver (an optical-to-electrical, or O–E converter), which leads to ultralow-energy signal conversion. By integrating these O–E/E–O devices, we demonstrate femtofarad ‘O–E–O transistors’ with optical signal gain that show various optical nonlinear functions, including as all-optical switches, wavelength converters and cascadable optical repeaters with a femtojoule-per-bit energy consumption. These femtofarad-scale O–E/E–O/O–E–O devices promise tightly coupled photonic–electronic integration for new fields of energy-saving information processing.

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Fig. 1: PhC-nanocavity EOM.
Fig. 2: PD-EOM integration.
Fig. 3: Operation dynamics for the O–E–O transistor.
Fig. 4: Short pulse response.
Fig. 5: Optical signal conversion efficiency.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author on reasonable request.


  1. 1.

    Williams, R. S. What’s next? Comput. Sci. Eng. 19, 7–13 (2017).

    Article  Google Scholar 

  2. 2.

    Miller, D. A. B. Device requirements for optical interconnects to silicon chips. Proc. IEEE 97, 1166–1185 (2009).

    Article  Google Scholar 

  3. 3.

    Miller, D. A. B. Attojoule optoelectronics for low-energy information processing and communications. J. Lightwave Technol. 35, 346–396 (2017).

    ADS  Article  Google Scholar 

  4. 4.

    Sorger, V. J. et al. Scaling vectors of attojoule per bit modulators. J. Opt. 20, 014012 (2018).

    ADS  Article  Google Scholar 

  5. 5.

    Krishnamoorthy, A. V. & Miller, D. A. B. Scaling optoelectronic-VLSI circuits into the 21st century: a technology roadmap. IEEE J. Sel. Top. Quant. Electron. 2, 55–76 (1996).

    ADS  Article  Google Scholar 

  6. 6.

    Timurdogan, E. et al. An ultralow power athermal silicon modulator. Nat. Commun. 5, 4008 (2014).

    ADS  Article  Google Scholar 

  7. 7.

    Settaluri, K. T. et al. Demonstration of an optical chip-to-chip link in a 3D integrated electronic-photonic platform. In 41st European Solid-State Circuits Conference (ESSCIRC) 156–159 (IEEE, 2015).

  8. 8.

    Nozaki, K. et al. Photonic-crystal nano-photodetector with ultrasmall capacitance for on-chip light-to-voltage conversion without an amplifier. Optica 3, 483–492 (2016).

    Article  Google Scholar 

  9. 9.

    Lentine, A. L. et al. Symmetric self-electrooptic effect device: optical set-reset latch, differential logic gate, and differential modulator detector. IEEE J. Quant. Electron. 25, 1928–1936 (1989).

    ADS  Article  Google Scholar 

  10. 10.

    Kasahara, K. Vstep-based smart pixels. IEEE J. Quant. Electron. 29, 757–768 (1993).

    ADS  Article  Google Scholar 

  11. 11.

    Matsuo, S., Amano, C. & Kurokawa, T. Photonic memory switch consisting of multiple quantum-well reflection modulator and heterojunction phototransistor. Appl. Phys. Lett. 60, 1547–1549 (1992).

    ADS  Article  Google Scholar 

  12. 12.

    Mccormick, F. B. et al. Six-stage digital free-space optical switching network using symmetrical self-electro-optic-effect devices. Appl. Opt. 32, 5153–5171 (1993).

    ADS  Article  Google Scholar 

  13. 13.

    Demir, H. V. et al. Multifunctional integrated photonic switches. IEEE J. Sel. Top. Quant. Electron. 11, 86–96 (2005).

    ADS  Article  Google Scholar 

  14. 14.

    Matsuo, S., Amano, C. & Kurokawa, T. Operation characteristics of 3-terminal hybrid structure with multiple-quantum-well reflection modulator and heterojunction phototransistor. IEEE Photon. Technol. Lett. 3, 330–332 (1991).

    ADS  Article  Google Scholar 

  15. 15.

    Kodama, S. et al. 2.3 picoseconds optical gate monolithically integrating photodiode and electroabsorption modulator. Electron. Lett. 37, 1185–1186 (2001).

    Article  Google Scholar 

  16. 16.

    Nozaki, K. et al. Ultracompact O-E-O converter based on a fF-capacitance nanophotonic integration. In Conference on Laser and Electro-Optics (CLEO) SF3A.3 (Optical Society of America, 2018).

  17. 17.

    Li, E. W., Gao, O., Chen, R. T. & Wang, A. X. Ultracompact silicon-conductive oxide nanocavity modulator with 0.02 lambda-cubic active volume. Nano Lett. 18, 1075–1081 (2018).

    ADS  Article  Google Scholar 

  18. 18.

    Haffner, C. et al. Low-loss plasmon-assisted electro-optic modulator. Nature 556, 483–486 (2018).

    ADS  Article  Google Scholar 

  19. 19.

    Nozaki, K. et al. Ultralow-energy electro-absorption modulator consisting of InGaAsP-embedded photonic-crystal waveguide. APL Photon. 2, 056105 (2017).

    ADS  Article  Google Scholar 

  20. 20.

    Miller, D. A. B. Energy consumption in optical modulators for interconnects. Opt. Express 20, A293–A308 (2012).

    ADS  Article  Google Scholar 

  21. 21.

    Koeber, S. et al. Femtojoule electro-optic modulation using a silicon-organic hybrid device. Light Sci. Appl. 4, e255 (2015).

    Article  Google Scholar 

  22. 22.

    Yoshimatsu, T., Kodama, S., Yoshino, K. & Ito, H. 100-Gb/s error-free wavelength conversion with a monolithic optical gate integrating a photodiode and electroabsorption modulator. IEEE Photon. Technol. Lett. 17, 2367–2369 (2005).

    ADS  Article  Google Scholar 

  23. 23.

    Sabnis, V. A. et al. Intimate monolithic integration of chip-scale photonic circuits. IEEE J. Sel. Top. Quant. Electron. 11, 1255–1265 (2005).

    ADS  Article  Google Scholar 

  24. 24.

    Nozaki, K., Matsuo, S., Shinya, A. & Notomi, M. Amplifier-free bias-free receiver based on low-capacitance nanophotodetector. IEEE J. Sel. Top. Quant. Electron. 24, 4900111 (2018).

    Article  Google Scholar 

  25. 25.

    Durhuus, T., Mikkelsen, B., Joergensen, C., Danielsen, S. L. & Stubkjaer, K. E. All-optical wavelength conversion by semiconductor optical amplifiers. J. Lightwave Technol. 14, 942–954 (1996).

    ADS  Article  Google Scholar 

  26. 26.

    Yamada, K. et al. All-optical efficient wavelength conversion using silicon photonic wire waveguide. IEEE Photon. Technol. Lett. 18, 1046–1048 (2006).

    ADS  Article  Google Scholar 

  27. 27.

    Shinya, A. et al. All-optical on-chip bit memory based on ultra high Q InGaAsP photonic crystal. Opt. Express 16, 19382–19387 (2008).

    ADS  Article  Google Scholar 

  28. 28.

    Gu, T. et al. Regenerative oscillation and four-wave mixing in graphene optoelectronics. Nat. Photon. 6, 554–559 (2012).

    ADS  Article  Google Scholar 

  29. 29.

    Nozaki, K. et al. Sub-femtojoule all-optical switching using a photonic-crystal nanocavity. Nat. Photon. 4, 477–483 (2010).

    ADS  Article  Google Scholar 

  30. 30.

    Woodward, T. K. et al. 1-Gb/s two-beam transimpedance smart-pixel optical receivers made from hybrid GaAs MQW modulators bonded to 0.8-mu m silicon CMOS. IEEE Photon. Technol. Lett. 8, 422–424 (1996).

    ADS  Article  Google Scholar 

  31. 31.

    Dummer, M. M., Klamkin, J., Tauke-Pedretti, A. & Coldren, L. A. 40 Gb/s field-modulated wavelength converters for all-optical packet switching. IEEE J. Sel. Top. Quant. Electron. 15, 494–503 (2009).

    ADS  Article  Google Scholar 

  32. 32.

    Miller, D. A. B. Are optical transistors the logical next step? Nat. Photon. 4, 3–5 (2010).

    ADS  Article  Google Scholar 

  33. 33.

    Nozaki, K. et al. Forward-biased nanophotonic detector for ultralow-energy dissipation receiver. APL Photon. 3, 046101 (2018).

    ADS  Article  Google Scholar 

  34. 34.

    Werner, S., Navaridas, J. & Lujan, M. A survey on optical network-on-chip architectures. ACM Comput. Surv. 50, 89 (2018).

    Google Scholar 

  35. 35.

    Touch, J. et al. Digital optical processing of optical communications: towards an optical turing machine. Nanophotonics 6, 507–530 (2017).

    Google Scholar 

  36. 36.

    Ishihara, T., Shinya, A., Inoue, K., Nozaki, K. & Notomi, M. An integrated nanophotonic parallel adder. ACM. J. Emerg. Technol. Comput. Syst. 14, 1–20 (2018).

    Article  Google Scholar 

  37. 37.

    Tait, A. N. et al. Neuromorphic photonic networks using silicon photonic weight banks. Sci. Rep. 7, 7430 (2017).

    ADS  Article  Google Scholar 

  38. 38.

    Shen, Y. C. et al. Deep learning with coherent nanophotonic circuits. Nat. Photon. 11, 441–446 (2017).

    ADS  Article  Google Scholar 

  39. 39.

    Ren, S. et al. Ge/SiGe quantum well waveguide modulator monolithically integrated with SOI waveguides. IEEE Photon. Technol. Lett. 24, 461–463 (2012).

    ADS  Article  Google Scholar 

  40. 40.

    Haffner, C. et al. All-plasmonic Mach-Zehnder modulator enabling optical high-speed communication at the microscale. Nat. Photon. 9, 525–518 (2015).

    ADS  Article  Google Scholar 

  41. 41.

    Sorger, V. J., Lanzillotti-Kimura, N. D., Ma, R. M. & Zhang, X. Ultra-compact silicon nanophotonic modulator with broadband response. Nanophotonics 1, 17–22 (2012).

    ADS  Article  Google Scholar 

  42. 42.

    Srinivasan, S. A. et al. 56 Gb/s germanium waveguide electro-absorption modulator. J. Lightwave Technol. 34, 419–424 (2016).

    ADS  Article  Google Scholar 

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We thank J. Asaoka, H. Onji, Y. Shouji and K. Ishibashi for their support in fabricating the device. This work was supported by CREST (JPMJCR15N4), the Japan Science and Technology Agency.

Author information




K.N. designed the devices and performed the measurements. S.M., T.F. and K.T. supported the design and fabrication of the samples. A.S. and E.K. supported the design and fabrication of the photonic-crystal structure. M.N. led the project. K.N. and M.N. conceived and planned this work, analysed the data and wrote the manuscript.

Corresponding authors

Correspondence to Kengo Nozaki or Masaya Notomi.

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The authors declare no competing interests.

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Supplementary Information

Supplementary Results and Discussion, Supplementary Figs. 1–12 and Supplementary Refs. 1–43.

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Nozaki, K., Matsuo, S., Fujii, T. et al. Femtofarad optoelectronic integration demonstrating energy-saving signal conversion and nonlinear functions. Nat. Photonics 13, 454–459 (2019).

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