toward higher-efficiency grating couplers
with greater resiliency to high-field hotspots
provides an achievable path to this estimated
value.
The fabricated devices accelerate electrons of
an initial energy of 83.4 keV by an inferred maxi-
mumenergygainof0.915keVover30mm, dem-
onstrating acceleration gradients of 30.5 MeV/m.
In this integrated form, these devices, alongside
focusing and bunching elements, can be cas-
caded to reach mega–electron volt-scale ener-
gies capitalizing on the inherent scalability of
photonic circuits.
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ACKNOWLEDGMENTS
Funding:We thank all the members of the Accelerator on a Chip
International Program for discussion and collaboration. This
work was supported by the Gordon and Betty Moore Foundation
(grant no. GBMF4744) and the U.S. Department of Energy,
Office of Science (grant nos. DE-AC02-76SF00515 and
DE-SC0009914). K.Y.Y. acknowledges funding from a Nano- and
Quantum Science and Engineering Postdoctoral Fellowship.
D.V. acknowledges funding from FWO and the European Union
Horizon 2020 Research and Innovation Program (under
Marie Sklodowska-Curie grant no. 665501). R.T. acknowledges a
Kailath Graduate Fellowship. Part of this work was performed at
the Stanford Nano Shared Facilities (SNSF)/Stanford
Nanofabrication Facility (SNF), which is supported by the
National Science Foundation under award no. ECCS-1542152.
Author contributions:N.V.S. performed and led the design,
simulation, and fabrication of the accelerator. K.Y.Y. and Y.M. assisted
with fabrication. D.V. assisted with design. K.J.L. and D.S.B.
conducted the electron acceleration experiment. R.J.E. performed
the particle-tracking simulations. L.S. provided the grating coupler
design code. R.T. assisted in simulation analysis. J.V., R.L.B.,
and O.S. organized the collaboration and supervised the experiments.
All authors participated in the discussion and interpretation of
the results.Competing interests:The authors declare no competing
interests.Data and materials availability:All data needed to
evaluate the conclusions in the paper are available in the main text
or the supplementary materials.SUPPLEMENTARY MATERIALS
science.sciencemag.org/content/367/6473/79/suppl/DC1
Materials and Methods
Supplementary Text
Figs. S1 to S4
References ( 37 – 39 )
Movies S1 and S2
5 July 2019; accepted 26 November 2019
10.1126/science.aay5734Sapraet al.,Science 367 ,79–83 (2020) 3 January 2020 4of4
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