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Thresholdless nanoscale coaxial lasers


The effects of cavity quantum electrodynamics (QED), caused by the interaction of matter and the electromagnetic field in subwavelength resonant structures, have been the subject of intense research in recent years1. The generation of coherent radiation by subwavelength resonant structures has attracted considerable interest, not only as a means of exploring the QED effects that emerge at small volume, but also for its potential in applications ranging from on-chip optical communication to ultrahigh-resolution and high-throughput imaging, sensing and spectroscopy. One such strand of research is aimed at developing the ‘ultimate’ nanolaser: a scalable, low-threshold, efficient source of radiation that operates at room temperature and occupies a small volume on a chip2. Different resonators have been proposed for the realization of such a nanolaser—microdisk3 and photonic bandgap4 resonators, and, more recently, metallic5,6, metallo-dielectric7,8,9,10 and plasmonic11,12 resonators. But progress towards realizing the ultimate nanolaser has been hindered by the lack of a systematic approach to scaling down the size of the laser cavity without significantly increasing the threshold power required for lasing. Here we describe a family of coaxial nanostructured cavities that potentially solve the resonator scalability challenge by means of their geometry and metal composition. Using these coaxial nanocavities, we demonstrate the smallest room-temperature, continuous-wave telecommunications-frequency laser to date. In addition, by further modifying the design of these coaxial nanocavities, we achieve thresholdless lasing with a broadband gain medium. In addition to enabling laser applications, these nanoscale resonators should provide a powerful platform for the development of other QED devices and metamaterials in which atom–field interactions generate new functionalities13,14.

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Figure 1: Nanoscale coaxial laser cavity.
Figure 2: Simulation of the electromagnetic properties of nanoscale coaxial cavities.
Figure 3: Optical characterization of nanoscale coaxial cavities of structure A at 4.5 K and room temperature, showing lasing.
Figure 4: Optical characterization of nanoscale coaxial cavities of structure B at 4.5 K, showing thresholdless lasing.


  1. Berman, P., ed. Cavity Quantum Electrodynamics (Academic, 1994)

  2. Noda, S. Seeking the ultimate nanolaser. Science 314, 260–261 (2006)

    Article  CAS  Google Scholar 

  3. McCall, S. L., Levi, A. F. J., Slusher, R. E., Pearton, S. J. & Logan, R. A. Whispering-gallery mode microdisk lasers. Appl. Phys. Lett. 60, 289–291 (1992)

    Article  ADS  CAS  Google Scholar 

  4. Painter, O. et al. Two-dimensional photonic band-gap defect mode laser. Science 284, 1819–1821 (1999)

    Article  CAS  Google Scholar 

  5. Hill, M. T. et al. Lasing in metallic-coated nano-cavities. Nature Photon. 1, 589–594 (2007)

    Article  ADS  CAS  Google Scholar 

  6. Walther, C., Scalari, G., Amanti, M. I., Beck, M. & Faist, J. Microcavity laser oscillating in a circuit-based resonator. Science 327, 1495–1497 (2010)

    Article  ADS  CAS  Google Scholar 

  7. Mizrahi, A. et al. Low threshold gain metal coated laser nanoresonators. Opt. Lett. 33, 1261–1263 (2008)

    Article  ADS  Google Scholar 

  8. Nezhad, M. P. et al. Room-temperature subwavelength metallo-dielectric lasers. Nature Photon. 4, 395–399 (2010)

    Article  ADS  CAS  Google Scholar 

  9. Yu, K., Lakhani, A. & Wu, M. C. Subwavelength metal-optic semiconductor nanopatch lasers. Opt. Express 18, 8790–8799 (2010)

    Article  ADS  CAS  Google Scholar 

  10. Ding, Q., Mizrahi, A., Fainman Y & Lomakin, V. Dielectric shielded nanoscale patch laser resonators. Opt. Lett. 36, 1812–1814 (2011)

    Article  ADS  Google Scholar 

  11. Noginov, M. A. et al. Demonstration of a spaser-based nanolaser. Nature 460, 1110–1112 (2009)

    Article  ADS  CAS  Google Scholar 

  12. Oulton, R. F. et al. Plasmon lasers at deep subwavelength scale. Nature 461, 629–632 (2009)

    Article  ADS  CAS  Google Scholar 

  13. Burgos, S. P., deWaele, R., Polman, A. & Atwater, H. A. A single-layer wide-angle negative-index metamaterial at visible frequencies. Nature Mater. 9, 407–412 (2010)

    Article  ADS  CAS  Google Scholar 

  14. Jacob, Z. & Shalaev, V. M. Plasmonics goes quantum. Science 334, 463–464 (2011)

    Article  ADS  CAS  Google Scholar 

  15. Vahala, K. J. Optical microcavities. Nature 424, 839–846 (2003)

    Article  ADS  CAS  Google Scholar 

  16. Yokoyama, H. Physics and device applications of optical microcavities. Science 256, 66–70 (1992)

    Article  ADS  CAS  Google Scholar 

  17. Bjork, G. & Yamamoto, Y. Analysis of semiconductor microcavity lasers using rate equations. IEEE J. Quantum Electron. 27, 2386–2396 (1991)

    Article  ADS  Google Scholar 

  18. Baida, F. I., Belkhir, A. & Van Labeke, D. Subwavelength metallic coaxial waveguides in the optical range: Role of the plasmonic modes. Phys. Rev. B 74, 205419 (2006)

    Article  ADS  Google Scholar 

  19. Feigenbaum, E. & Orenstein, M. Ultrasmall volume plasmons, yet with complete retardation effects. Phys. Rev. Lett. 101, 163902 (2008)

    Article  ADS  Google Scholar 

  20. Benzaquen, R. et al. Alloy broadening in photoluminescence spectra of GaxIn1−xAsyP1−y lattice matched to InP. J. Appl. Phys. 75, 2633–2639 (1994)

    Article  ADS  CAS  Google Scholar 

  21. Bayer, M. et al. Inhibition and enhancement of the spontaneous emission of quantum dots in structured microresonators. Phys. Rev. Lett. 86, 3168–3171 (2001)

    Article  ADS  CAS  Google Scholar 

  22. Vuckovic, J., Painter, O., Xu, Y., Yariv, A. & Scherer, A. Finite-difference time-domain calculation of the spontaneous emission coupling factor in optical microcavities. IEEE J. Quantum Electron. 35, 1168–1175 (1999)

    Article  ADS  CAS  Google Scholar 

  23. Schawlow, A. L. & Townes, C. H. Infrared and optical masers. Phys. Rev. 112, 1940–1949 (1958)

    Article  ADS  CAS  Google Scholar 

  24. Henry, C. Theory of the linewidth of semiconductor lasers. IEEE J. Quantum Electron. 18, 259–264 (1982)

    Article  ADS  Google Scholar 

  25. Björk, G., Karlsson, A. & Yamamoto, Y. On the linewidth of microcavity lasers. Appl. Phys. Lett. 60, 304–306 (1992)

    Article  ADS  Google Scholar 

  26. Rice, P. R. & Carmichael, H. J. Photon statistics of a cavity-QED laser: a comment on the laser-phase-transition analogy. Phys. Rev. A 50, 4318–4329 (1994)

    Article  ADS  CAS  Google Scholar 

  27. Pedrotti, L. M., Sokol, M. & Rice, P. R. Linewidth of four-level microcavity lasers. Phys. Rev. A 59, 2295–2301 (1999)

    Article  ADS  CAS  Google Scholar 

  28. Roy-Choudhury, K. & Levi, A. F. J. Quantum fluctuations and saturable absorption in mesoscale lasers. Phys. Rev. A 83, 043827 (2011)

    Article  ADS  Google Scholar 

  29. Strauf, S. et al. Self-tuned quantum dot gain in photonic crystal lasers. Phys. Rev. Lett. 96, 127404 (2006)

    Article  ADS  CAS  Google Scholar 

  30. Chang, S. W. & Chuang, S. L. Fundamental formulation for plasmonic nanolasers. IEEE J. Quantum Electron. 45, 1014–1023 (2009)

    Article  ADS  CAS  Google Scholar 

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We acknowledge support from the Defense Advanced Research Projects Agency (DARPA), the National Science Foundation (NSF), the NSF Center for Integrated Access Networks (CIAN), the Cymer Corporation and the US Army Research Office. M. Khajavikhan thanks the personnel of the UCSD Nano3 facilities for their help and support, T. Javidi and J. Leger for technical discussions regarding the analysis of the data and profile of the beam, and graduate student J. Shane for her help with editing the document.

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Authors and Affiliations



M. Khajavikhan conceived the idea of thresholdless laser using nanoscale coaxial structures. The electromagnetic design, simulation, and analysis of the structures were carried out by M. Khajavikhan, A.M. and V.L. Fabrication of the devices was carried out by M. Khajavikhan and J.H.L. The optical measurements were performed by A.S. and M. Khajavikhan. The rate equation model was developed by M. Katz. The optical characterization and analysis of laser behaviour was carried out by M. Khajavikhan, M. Katz, A.M., B.S. and Y.F. The manuscript was written by M. Khajavikhan, with contributions from A.M., M. Katz, Y.F., A.S., B.S. and V.L.

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Correspondence to M. Khajavikhan.

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The authors declare no competing financial interests.

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Khajavikhan, M., Simic, A., Katz, M. et al. Thresholdless nanoscale coaxial lasers. Nature 482, 204–207 (2012).

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