Integrated optical modulators with high modulation speed, small footprint and large optical bandwidth are poised to be the enabling devices for on-chip optical interconnects1,2. Semiconductor modulators have therefore been heavily researched over the past few years. However, the device footprint of silicon-based modulators is of the order of millimetres, owing to its weak electro-optical properties3. Germanium and compound semiconductors, on the other hand, face the major challenge of integration with existing silicon electronics and photonics platforms4,5,6. Integrating silicon modulators with high-quality-factor optical resonators increases the modulation strength, but these devices suffer from intrinsic narrow bandwidth and require sophisticated optical design; they also have stringent fabrication requirements and limited temperature tolerances7. Finding a complementary metal-oxide-semiconductor (CMOS)-compatible material with adequate modulation speed and strength has therefore become a task of not only scientific interest, but also industrial importance. Here we experimentally demonstrate a broadband, high-speed, waveguide-integrated electroabsorption modulator based on monolayer graphene. By electrically tuning the Fermi level of the graphene sheet, we demonstrate modulation of the guided light at frequencies over 1 GHz, together with a broad operation spectrum that ranges from 1.35 to 1.6 µm under ambient conditions. The high modulation efficiency of graphene results in an active device area of merely 25 µm2, which is among the smallest to date. This graphene-based optical modulation mechanism, with combined advantages of compact footprint, low operation voltage and ultrafast modulation speed across a broad range of wavelengths, can enable novel architectures for on-chip optical communications.
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Miller, D. A. B. Are optical transistors the logical next step? Nature Photon. 4, 3–5 (2010)
Reed, G. T., Mashanovich, G., Gardes, F. Y. & Thomson, D. J. Silicon optical modulators. Nature Photon. 4, 518–526 (2010)
Liu, A. S. et al. A high-speed silicon optical modulator based on a metal-oxide-semiconductor capacitor. Nature 427, 615–618 (2004)
Kuo, Y. H. et al. Strong quantum-confined Stark effect in germanium quantum-well structures on silicon. Nature 437, 1334–1336 (2005)
Liu, J. et al. Waveguide-integrated, ultralow-energy GeSi electro-absorption modulators. Nature Photon. 2, 433–437 (2008)
Miller, D. A. B. et al. Band-edge electroabsorption in quantum well structures — the quantum-confined Stark-effect. Phys. Rev. Lett. 53, 2173–2176 (1984)
Xu, Q., Schmidt, B., Pradhan, S. & Lipson, M. Micrometre-scale silicon electro-optic modulator. Nature 435, 325–327 (2005)
Novoselov, K. S. Electric field effect in atomically thin carbon films. Science 306, 666–669 (2004)
Geim, A. K. & Novoselov, K. S. The rise of graphene. Nature Mater. 6, 183–191 (2007)
Schwierz, F. Graphene transistors. Nature Nanotechnol. 5, 487–496 (2010)
Bonaccorso, F., Sun, Z., Hasan, T. & Ferrari, A. Graphene photonics and optoelectronics. Nature Photon. 4, 611–622 (2010)
Liao, L. et al. High-speed graphene transistors with a self-aligned nanowire gate. Nature 467, 305–308 (2010)
Avouris, P., Chen, Z. H. & Perebeinos, V. Carbon-based electronics. Nature Nanotechnol. 2, 605–615 (2007)
Wang, F. et al. Gate-variable optical transitions in graphene. Science 320, 206–209 (2008)
Li, Z. Q. et al. Dirac charge dynamics in graphene by infrared spectroscopy. Nature Phys. 4, 532–535 (2008)
Xia, F. N., Mueller, T., Lin, Y. M., Valdes-Garcia, A. & Avouris, P. Ultrafast graphene photodetector. Nature Nanotechnol. 4, 839–843 (2009)
Xu, X., Gabor, N. M., Alden, J. S., van der Zande, A. M. & McEuen, P. L. Photo-thermoelectric effect at a graphene interface junction. Nano Lett. 10, 562–566 (2010)
Nair, R. R. et al. Fine structure constant defines visual transparency of graphene. Science 320, 1308 (2008)
Mak, K. F. et al. Measurement of the optical conductivity of graphene. Phys. Rev. Lett. 101, 196405 (2008)
Bolotin, K. I. et al. Ultrahigh electron mobility in suspended graphene. Solid State Commun. 146, 351–355 (2008)
Du, X., Skachko, I., Barker, A. & Andrei, E. Y. Approaching ballistic transport in suspended graphene. Nature Nanotechnol. 3, 491–495 (2008)
Kampfrath, T., Perfetti, L., Schapper, F., Frischkorn, C. & Wolf, M. Strongly coupled optical phonons in the ultrafast dynamics of the electronic energy and current relaxation in graphite. Phys. Rev. Lett. 95, 187403 (2005)
Kim, K. S. et al. Large-scale pattern growth of graphene films for stretchable transparent electrodes. Nature 457, 706–710 (2009)
Bae, S. et al. Roll-to-roll production of 30-inch graphene films for transparent electrodes. Nature Nanotechnol. 5, 574–578 (2010)
Reina, A. et al. Large area, few-layer graphene films on arbitrary substrates by chemical vapor deposition. Nano Lett. 9, 30–35 (2009)
Li, X. et al. Large-area synthesis of high-quality and uniform graphene films on copper foils. Science 324, 1312–1314 (2009)
Zhang, Y. B., Brar, V. W., Girit, C., Zettl, A. & Crommie, M. F. Origin of spatial charge inhomogeneity in graphene. Nature Phys. 5, 722–726 (2009)
Jablan, M., Buljan, H. & Soljacˇic´, M. Plasmonics in graphene at infrared frequencies. Phys. Rev. B 80, 245435 (2009)
Zhou, S. Y. et al. First direct observation of Dirac fermions in graphite. Nature Phys. 2, 595–599 (2006)
Rogers, J. A., Someya, T. & Huang, Y. G. Materials and mechanics for stretchable electronics. Science 327, 1603–1607 (2010)
This work was supported by the National Science Foundation Nano-scale Science and Engineering Center (NSF-NSEC) for Scalable and Integrated Nano Manufacturing (SINAM) (grant no. CMMI-0751621) and by the US Department of Energy, Basic Energy Sciences Energy Frontier Research Center (DoE-LMI-EFRC) under award DOE DE-AC02-05CH11231. M.L. thanks Y. Rao for discussions.
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Liu, M., Yin, X., Ulin-Avila, E. et al. A graphene-based broadband optical modulator. Nature 474, 64–67 (2011). https://doi.org/10.1038/nature10067
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