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Graphene electro-optic modulator with 30 GHz bandwidth


Graphene has generated exceptional interest as an optoelectronic material1,2 because its high carrier mobility3,4 and broadband absorption5 promise to make extremely fast and broadband electro-optic devices possible6,7,8,9. Electro-optic graphene modulators previously reported, however, have been limited in bandwidth to a few gigahertz10,11,12,13,14,15 because of the large capacitance required to achieve reasonable voltage swings. Here, we demonstrate a graphene electro-optic modulator based on resonator loss modulation at critical coupling16 that shows drastically increased speed and efficiency. Our device operates with a 30 GHz bandwidth and with a state-of-the-art modulation efficiency of 15 dB per 10 V. We also show the first high-speed large-signal operation in a graphene modulator, paving the way for fast digital communications using this platform. The modulator uniquely uses silicon nitride waveguides, an otherwise completely passive material platform, with promising applications for ultra-low-loss broadband structures and nonlinear optics.

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Figure 1: Critical coupling effect.
Figure 2: Device design.
Figure 3: Electrical response.


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The authors thank M. Blees and P.L. McEuen for discussions and graphene samples. This work was supported in part by the National Science Foundation (NSF) through CIAN ERC (grant no. EEC-0812072). C.T.P. acknowledges support from a NSF Graduate Research Fellowship (grant no. DGE-1144153). This work was performed in part at the Cornell NanoScale Facility, a member of the National Nanotechnology Infrastructure Network, which is supported by the NSF (grant no. ECCS-0335765). This work also made use of the Cornell Center for Materials Research Shared Facilities, which are supported through the NSF MRSEC program (DMR-1120296).

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Authors and Affiliations



C.T.P. conceived the work, designed and fabricated the devices and prepared the manuscript. C.T.P. and Y.-H.D.L. performed the high-speed measurements. J.C. discussed the device design and assisted with sample fabrication. M.L. supervised the project and edited the manuscript.

Corresponding author

Correspondence to Michal Lipson.

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Competing interests

C.T.P. and M.L. are named inventors on US provisional patent application no. 62/076,938 regarding the technology reported in this Letter.

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Phare, C., Daniel Lee, YH., Cardenas, J. et al. Graphene electro-optic modulator with 30 GHz bandwidth. Nature Photon 9, 511–514 (2015).

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