Continuous-wave room-temperature diamond maser

  • Nature volume 555, pages 493496 (22 March 2018)
  • doi:10.1038/nature25970
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The maser—the microwave progenitor of the optical laser—has been confined to relative obscurity owing to its reliance on cryogenic refrigeration and high-vacuum systems. Despite this, it has found application in deep-space communications and radio astronomy owing to its unparalleled performance as a low-noise amplifier and oscillator. The recent demonstration of a room-temperature solid-state maser that utilizes polarized electron populations within the triplet states of photo-excited pentacene molecules in a p-terphenyl host1,2,3 paves the way for a new class of maser. However, p-terphenyl has poor thermal and mechanical properties, and the decay rates of the triplet sublevel of pentacene mean that only pulsed maser operation has been observed in this system. Alternative materials are therefore required to achieve continuous emission: inorganic materials that contain spin defects, such as diamond4,5,6 and silicon carbide7, have been proposed. Here we report a continuous-wave room-temperature maser oscillator using optically pumped nitrogen–vacancy defect centres in diamond. This demonstration highlights the potential of room-temperature solid-state masers for use in a new generation of microwave devices that could find application in medicine, security, sensing and quantum technologies.

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We thank J. Hall and M. Markham (Element 6 Ltd) for supplying the diamond samples, P. French and R. Taylor (Photonics Group at Imperial College London) for lending us their continuous-wave laser, and E. Bauch (Harvard University) for discussions. We also thank M. Lennon (IC), D. Halpin and D. Farquharson (UCL) for manufacturing the cavity components. This work was supported by the UK Engineering and Physical Sciences Research Council through grants EP/K011987/1 (IC) and EP/K011804/1 (UCL). We also acknowledge support from the Henry Royce Institute.

Author information


  1. Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, UK

    • Jonathan D. Breeze
    • , Juna Sathian
    •  & Neil McN. Alford
  2. London Centre for Nanotechnology, Imperial College London, Exhibition Road, London SW7 2AZ, UK

    • Jonathan D. Breeze
    •  & Neil McN. Alford
  3. Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 8BT, UK

    • Enrico Salvadori
    •  & Christopher W. M. Kay
  4. London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH, UK

    • Enrico Salvadori
    •  & Christopher W. M. Kay
  5. School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK

    • Enrico Salvadori
  6. Department of Chemistry, University of Saarland, 66123 Saarbrücken, Germany

    • Christopher W. M. Kay


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J.D.B. conceived the study, developed the theory, designed the maser cavity, devised the experiment and wrote software for collecting experimental data. J.D.B. and C.W.M.K. developed the experimental design and performed experiments with input from E.S. and J.S. J.D.B. interpreted the results with input from E.S. and C.W.M.K. J.S. characterized the diamond NV concentration by optical means and developed the optical pumping scheme. J.D.B., E.S. and C.W.M.K. characterized the diamonds using EPR. J.D.B. wrote the paper with assistance from C.W.M.K. and with additional editing by E.S. and N.M.A.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Jonathan D. Breeze.

Reviewer Information Nature thanks A. Blank, F. Jelezko and R.-B. Liu for their contribution to the peer review of this work.

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