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Published May 3, 2018 | Submitted + Supplemental Material
Journal Article Open

An optical-frequency synthesizer using integrated photonics


Optical-frequency synthesizers, which generate frequency-stable light from a single microwave-frequency reference, are revolutionizing ultrafast science and metrology, but their size, power requirement and cost need to be reduced if they are to be more widely used. Integrated-photonics microchips can be used in high-coherence applications, such as data transmission, highly optimized physical sensors and harnessing quantum states, to lower cost and increase efficiency and portability. Here we describe a method for synthesizing the absolute frequency of a lightwave signal, using integrated photonics to create a phase-coherent microwave-to-optical link. We use a heterogeneously integrated iii–v/silicon tunable laser, which is guided by nonlinear frequency combs fabricated on separate silicon chips and pumped by off-chip lasers. The laser frequency output of our optical-frequency synthesizer can be programmed by a microwave clock across 4 terahertz near 1,550 nanometres (the telecommunications C-band) with 1 hertz resolution. Our measurements verify that the output of the synthesizer is exceptionally stable across this region (synthesis error of 7.7 × 10^(−15) or below). Any application of an optical-frequency source could benefit from the high-precision optical synthesis presented here. Leveraging high-volume semiconductor processing built around advanced materials could allow such low-cost, low-power and compact integrated-photonics devices to be widely used.

Additional Information

© 2018 Macmillan Publishers Limited, part of Springer Nature. Received: 21 August 2017; Accepted: 22 January 2018; Published online: 25 April 2018. Data availability: The data sets generated and/or analysed during the current study are available from the corresponding authors on reasonable request. We thank Srico, Inc. for use of the waveguide PPLN device, Aurrion Inc. for use of the iii–v/Si tunable laser, and D. Hickstein, T. Dunker, A. Wallin, D. Carlson and Z. Newman for comments on the experiment. N.V. acknowledges support from the Swiss National Science Foundation (SNSF). This research is supported by the Defense Advanced Research Projects Agency DODOS program and NIST. We thank R. Lutwak and the DODOS program management team for discussions throughout the experiment. Reviewer Information: Nature thanks M. Lipson, D. Moss and the other anonymous reviewer(s) for their contribution to the peer review of this work. Author Contributions: D.T.S., T.D., T.C.B. and J.S. contributed equally to performing the system measurements and analysing the experimental results. D.T.S., S.A.D. and S.B.P. prepared the manuscript. The integrated devices were fabricated and tested by Q.L., D.W., B.R.I. and K.S. (Si3N4); A.B., N.V., T.K., L.C. and E. N. (iii–v/Si); and S.H.L., D.Y.O., M.S., K.Y.Y. and K.V. (SiO2). N.V., L.C.S., C.F., M.H.P.F. and A.B. provided measurement support. T.J.K, E.N., K.V., K.S., N.R.N., L.T., J.E.B., S.A.D. and S.B.P. supervised and led the scientific collaboration. This work is an official contribution of the NIST; not subject to copyright in the United States. The use of trade names is not intended to imply recommendation or endorsement by NIST, nor is it intended to imply that the materials or equipment identified are necessarily the best available for the purpose. The authors declare no competing financial interests.

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August 19, 2023
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