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Ultrafast and energy-efficient all-optical switching with graphene-loaded deep-subwavelength plasmonic waveguides


All-optical switches have attracted attention because they can potentially overcome the speed limitation of electric switches. However, ultrafast, energy-efficient all-optical switches have been challenging to realize owing to the intrinsically small optical nonlinearity in existing materials. As a solution, we propose the use of graphene-loaded deep-subwavelength plasmonic waveguides (30 × 20 nm2). Thanks to extreme light confinement, we have greatly enhanced optical nonlinear absorption in graphene, and achieved ultrafast all-optical switching with a switching energy of 35 fJ and a switching time of 260 fs. The switching energy is four orders of magnitude smaller than that in previous graphene-based devices and is the smallest value reported for any all-optical switch operating at a few picoseconds or less. This device can be efficiently connected to conventional silicon waveguides and used in silicon photonic integrated circuits. We believe that this graphene-based device will pave the way towards on-chip ultrafast and energy-efficient photonic processing.

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Fig. 1: Schematic and simulation of a graphene-loaded metal–insulator–metal WG for all-optical control.
Fig. 2: SEM images of the fabricated samples.
Fig. 3: Measured linear absorption of graphene-loaded MIM-WGs.
Fig. 4: Saturable absorption and demonstration of all-optical switching.
Fig. 5: Demonstration of all-optical switching with femtosecond laser pulses.

Data availability

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


  1. 1.

    International Roadmap for Devices and Systems (2017).

  2. 2.

    Werner, S., Navaridas, J. & Luján, M. A survey on optical network-on-chip architectures. ACM Comput. Surv. 50, 1–37 (2017).

    Article  Google Scholar 

  3. 3.

    Iizuka, N., Kaneko, K. & Suzuki, N. All-optical switch utilizing intersubband transition in GaN quantum wells. IEEE J. Quantum Electron. 42, 765–771 (2006).

    ADS  Article  Google Scholar 

  4. 4.

    Cong, G. W., Akimoto, R., Akita, K., Hasama, T. & Ishikawa, H. Low-saturation-energy-driven ultrafast all-optical switching operation in (CdS/ZnSe)/BeTe intersubband transition. Opt. Express 15, 12123–12130 (2007).

    ADS  Article  Google Scholar 

  5. 5.

    Takahashi, R., Itoh, H. & Iwamura, H. Ultrafast high-contrast all-optical switching using spin polarization in low-temperature-grown multiple quantum wells. Appl. Phys. Lett. 77, 2958–2960 (2000).

    ADS  Article  Google Scholar 

  6. 6.

    Morita, K., Takahashi, T., Kitada, T. & Isu, T. Enhanced optical Kerr signal of GaAs/AlAs multilayer cavity with InAs quantum dots embedded in strain-relaxed barriers. Appl. Phys. Express 2, 082001 (2009).

    ADS  Article  Google Scholar 

  7. 7.

    Tan, W. J., Ma, J., Zheng, Y. P. & Tong, J. Y. Femtosecond optical Kerr gate with double gate pulses. IEEE Photon. Technol. Lett. 30, 266–269 (2018).

    ADS  Article  Google Scholar 

  8. 8.

    Yang, Y. M. et al. Femtosecond optical polarization switching using a cadmium oxide-based perfect absorber. Nat. Photon. 11, 390–395 (2017).

    ADS  Article  Google Scholar 

  9. 9.

    Liu, Y. et al. 10 fs ultrafast all-optical switching in polystyrene nonlinear photonic crystals. Appl. Phys. Lett. 95, 131116 (2009).

    ADS  Article  Google Scholar 

  10. 10.

    Ren, M. et al. Nanostructured plasmonic medium for terahertz bandwidth all-optical switching. Adv. Mater. 23, 5540–5544 (2011).

    Article  Google Scholar 

  11. 11.

    Boyd, R. W. Nonlinear Optics 3rd edn (Academic, 2008).

  12. 12.

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

    ADS  Article  Google Scholar 

  13. 13.

    Novoselov, K. S. et al. Electric field effect in atomically thin carbon films. Science 306, 666–669 (2004).

    ADS  Article  Google Scholar 

  14. 14.

    Geim, A. K. & Novoselov, K. S. The rise of graphene. Nat. Mater. 6, 183–191 (2007).

    ADS  Article  Google Scholar 

  15. 15.

    Bonaccorso, F., Sun, Z., Hasan, T. & Ferrari, A. C. Graphene photonics and optoelectronics. Nat. Photon. 4, 611–622 (2010).

    ADS  Article  Google Scholar 

  16. 16.

    Keller, U. et al. Semiconductor saturable absorber mirrors (SESAMs) for femtosecond to nanosecond pulse generation in solid-state lasers. IEEE J. Sel. Top. Quantum Electron. 2, 435–453 (1996).

    ADS  Article  Google Scholar 

  17. 17.

    Keller, U. & Tropper, A. C. Passively modelocked surface-emitting semiconductor lasers. Phys. Rep. 429, 67–120 (2006).

    ADS  Article  Google Scholar 

  18. 18.

    Dawlaty, J. M., Shivaraman, S., Chandrashekhar, M., Rana, F. & Spencer, M. G. Measurement of ultrafast carrier dynamics in epitaxial graphene. Appl. Phys. Lett. 92, 042116 (2008).

    ADS  Article  Google Scholar 

  19. 19.

    Kumar, S. et al. Femtosecond carrier dynamics and saturable absorption in graphene suspensions. Appl. Phys. Lett. 95, 191911 (2009).

    ADS  Article  Google Scholar 

  20. 20.

    Dawlaty, J. M. et al. Measurement of the optical absorption spectra of epitaxial graphene from terahertz to visible. Appl. Phys. Lett. 93, 131905 (2008).

    ADS  Article  Google Scholar 

  21. 21.

    Alexander, K., Savostianova, N. A., Mikhailov, S. A., Van Thourhout, D. & Kuyken, B. Gate-tunable nonlinear refraction and absorption in graphene-covered silicon nitride waveguides. ACS Photon. 5, 4944–4950 (2018).

    Article  Google Scholar 

  22. 22.

    Novoselov, K. S. et al. Two-dimensional gas of massless Dirac fermions in graphene. Nature 438, 197–200 (2005).

    ADS  Article  Google Scholar 

  23. 23.

    Zhou, S. Y. et al. First direct observation of Dirac fermions in graphite. Nat. Phys. 2, 595–599 (2006).

    Article  Google Scholar 

  24. 24.

    Bao, Q. et al. Atomic-layer graphene as a saturable absorber for ultrafast pulsed lasers. Adv. Funct. Mater. 19, 3077–3083 (2009).

    Article  Google Scholar 

  25. 25.

    Liu, M. et al. A graphene-based broadband optical modulator. Nature 474, 64–67 (2011).

    ADS  Article  Google Scholar 

  26. 26.

    Phare, C. T., Lee, Y. H. D., Cardenas, J. & Lipson, M. Graphene electro-optic modulator with 30 GHz bandwidth. Nat. Photon. 9, 511–514 (2015).

    ADS  Article  Google Scholar 

  27. 27.

    Ding, Y. et al. Effective electro-optical modulation with high extinction ratio by a graphene-silicon microring resonator. Nano Lett. 15, 4393–4400 (2015).

    ADS  Article  Google Scholar 

  28. 28.

    Youngblood, N., Anugrah, Y., Ma, R., Koester, S. J. & Li, M. Multifunctional graphene optical modulator and photodetector integrated on silicon waveguides. Nano Lett. 14, 2741–2746 (2014).

    ADS  Article  Google Scholar 

  29. 29.

    Liu, Z. B. et al. Broadband all-optical modulation using a graphene-covered-microfiber. Laser Phys. Lett. 10, 065901 (2013).

    ADS  Article  Google Scholar 

  30. 30.

    Ansell, D. et al. Hybrid graphene plasmonic waveguide modulators. Nat. Commun. 6, 8846 (2015).

    ADS  Article  Google Scholar 

  31. 31.

    Ding, Y. et al. Efficient electro-optic modulation in low-loss graphene-plasmonic slot waveguides. Nanoscale 9, 15576–15581 (2017).

    Article  Google Scholar 

  32. 32.

    Sun, Z., Martinez, A. & Wang, F. Optical modulators with 2D layered materials. Nat. Photon. 10, 227–238 (2016).

    ADS  Article  Google Scholar 

  33. 33.

    Li, W. et al. Ultrafast all-optical graphene modulator. Nano Lett. 14, 955–959 (2014).

    ADS  Article  Google Scholar 

  34. 34.

    Pile, D. F. P. et al. Two-dimensionally localized modes of a nanoscale gap plasmon waveguide. Appl. Phys. Lett. 87, 261114 (2005).

    ADS  Article  Google Scholar 

  35. 35.

    Veronis, G. & Fan, S. Guided subwavelength plasmonic mode supported by a slot in a thin metal film. Opt. Lett. 30, 3359–3361 (2005).

    ADS  Article  Google Scholar 

  36. 36.

    Ono, M. et al. Deep-subwavelength plasmonic mode converter with large size reduction for Si-wire waveguide. Optica 3, 999–1005 (2016).

    ADS  Article  Google Scholar 

  37. 37.

    Veronis, G. & Fan, S. H. Modes of subwavelength plasmonic slot waveguides. J. Lightwave Technol. 25, 2511–2521 (2007).

    ADS  Article  Google Scholar 

  38. 38.

    Ma, Z. Z., Tahersima, M. H., Khan, S. & Sorger, V. J. Two-dimensional material-based mode confinement engineering in electro-optic modulators. IEEE J. Sel. Top. Quantum Electron. 23, 3400208 (2017).

    Google Scholar 

  39. 39.

    Kou, R. et al. Characterization of optical absorption and polarization dependence of single-layer graphene integrated on a silicon wire waveguide. Jpn J. Appl. Phys. 52, 060203 (2013).

    ADS  Article  Google Scholar 

  40. 40.

    Wang, J., Cheng, Z. Z., Tsang, H. K. & Shu, C. In-plane saturable absorption of graphene on a silicon slot waveguide. In Proc. OECC/PS2016 ThE3-2 (IEEE, 2016).

  41. 41.

    Tanabe, T., Taniyama, H. & Notomi, M. Carrier diffusion and recombination in photonic crystal nanocavity optical switches. J. Lightwave Technol. 26, 1396–1403 (2008).

    ADS  Article  Google Scholar 

  42. 42.

    Ruzicka, B. A. et al. Hot carrier diffusion in graphene. Phys. Rev. B 82, 195414 (2010).

    ADS  Article  Google Scholar 

  43. 43.

    Baek, I. H. et al. Efficient mode-locking of sub-70-fs Ti:sapphire laser by graphene saturable absorber. Appl. Phys. Express 5, 032701 (2012).

    ADS  Article  Google Scholar 

  44. 44.

    Xu, S. C. et al. Sapphire-based graphene saturable absorber for long-time working femtosecond lasers. Opt. Lett. 39, 2707–2710 (2014).

    ADS  Article  Google Scholar 

  45. 45.

    Vo, T. D. et al. Photonic chip based transmitter optimization and receiver demultiplexing of a 1.28 Tbit/s OTDM signal. Opt. Express 18, 17252–17261 (2010).

    ADS  Article  Google Scholar 

  46. 46.

    Ji, H. et al. Optical waveform sampling and error-free demultiplexing of 1.28 Tbit/s serial data in a silicon nanowire. In Proc. Optical Fiber Communication Conf. PDPC7 (OSA, 2010).

  47. 47.

    Rana, F. Electron–hole generation and recombination rates for Coulomb scattering in graphene. Phys. Rev. B 76, 155431 (2007).

    ADS  Article  Google Scholar 

  48. 48.

    Mihnev, M. T. et al. Microscopic origins of the terahertz carrier relaxation and cooling dynamics in graphene. Nat. Commun. 7, 11617 (2016).

    ADS  Article  Google Scholar 

  49. 49.

    Lu, J. & Liu, H. A critical review on the carrier dynamics in 2D layered materials investigated using THz spectroscopy. Opt. Commun. 406, 24–35 (2018).

    ADS  Article  Google Scholar 

  50. 50.

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

    ADS  Article  Google Scholar 

  51. 51.

    Bagherian, H. et al. On-chip optical convolutional neural networks. Preprint at (2018).

  52. 52.

    Hanson, G. W. Dyadic Green’s functions and guided surface waves for a surface conductivity model of graphene. J. Appl. Phys. 103, 064302 (2008).

    ADS  Article  Google Scholar 

  53. 53.

    Johnson, P. B. & Christy, R. W. Optical constants of the noble metals. Phys. Rev. B 6, 4370–4379 (1972).

    ADS  Article  Google Scholar 

  54. 54.

    Palik, E. D. Handbook of Optical Constants of Solids (Academic, 1985).

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We thank E. Kuramochi and T. Tamamura for support with the fabrication, K. Takata for support with the measurements and A. Shinya, N. Matsuda and Y. Ogawa for discussions. This work was supported by JSPS KAKENHI grant no. JP15H05735.

Author information




M.O. designed and fabricated the sample, performed the experiment, analysed the data and wrote the manuscript. M.H. and M.T. numerically designed and fabricated the sample, performed the experiment and analysed the data. K.N. supported the measurement set-up and the discussion. H.S. and H.C. supported the graphene process and the discussion. M.N. conceived the work, designed the sample, analysed the data, wrote the manuscript and led the project.

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Correspondence to Masaaki Ono or Masaya Notomi.

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Supplementary Information

Performance comparison, graphene absorption analysis and insertion loss.

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Ono, M., Hata, M., Tsunekawa, M. et al. Ultrafast and energy-efficient all-optical switching with graphene-loaded deep-subwavelength plasmonic waveguides. Nat. Photonics 14, 37–43 (2020).

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