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Monolayer semiconductor nanocavity lasers with ultralow thresholds


Engineering the electromagnetic environment of a nanometre-scale light emitter by use of a photonic cavity can significantly enhance its spontaneous emission rate, through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter1,2,3,4,5, providing a low-threshold laser system with small footprint, low power consumption and ultrafast modulation. An ultralow-threshold nanoscale laser has been successfully developed by embedding quantum dots into a photonic crystal cavity (PCC)6,7,8. However, several challenges impede the practical application of this architecture, including the random positions and compositional fluctuations of the dots7, extreme difficulty in current injection8, and lack of compatibility with electronic circuits7,8. Here we report a new lasing strategy: an atomically thin crystalline semiconductor—that is, a tungsten diselenide monolayer—is non-destructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PCC. A continuous-wave nanolaser operating in the visible regime is thereby achieved with an optical pumping threshold as low as 27 nanowatts at 130 kelvin, similar to the value achieved in quantum-dot PCC lasers7. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within one nanometre of the PCC surface. The surface-gain geometry gives unprecedented accessibility and hence the ability to tailor gain properties via external controls such as electrostatic gating and current injection, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.

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Figure 1: Hybrid monolayer WSe2–PCC nanolasers.
Figure 2: Lasing characteristics.
Figure 3: Spatially resolved emission and temperature-dependent device behaviour.
Figure 4: Reproducibility and scalability of the 2D nanolasers.

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

    Article  ADS  CAS  Google Scholar 

  2. Lu, Y.-J. et al. Plasmonic nanolaser using epitaxially grown silver film. Science 337, 450–453 (2012)

    Article  ADS  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

  7. Strauf, S. & Jahnke, F. Single quantum dot nanolaser. Laser Photon. Rev. 5, 607–633 (2011)

    Article  ADS  Google Scholar 

  8. Ellis, B. et al. Ultralow-threshold electrically pumped quantum-dot photonic-crystal nanocavity laser. Nature Photon. 5, 297–300 (2011)

    Article  ADS  CAS  Google Scholar 

  9. Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010)

    Article  ADS  Google Scholar 

  10. Splendiani, A. et al. Emerging photoluminescence in monolayer MoS2 . Nano Lett. 10, 1271–1275 (2010)

    Article  ADS  CAS  Google Scholar 

  11. Mak, K. F. et al. Tightly bound trions in monolayer MoS2 . Nature Mater. 12, 207–211 (2013)

    Article  ADS  CAS  Google Scholar 

  12. Ross, J. S. et al. Electrical control of neutral and charged excitons in a monolayer semiconductor. Nature Commun. 4, 1474 (2013)

    Article  ADS  Google Scholar 

  13. Jones, A. M. et al. Optical generation of excitonic valley coherence in monolayer WSe2 . Nature Nanotechnol. 8, 634–638 (2013)

    Article  ADS  CAS  Google Scholar 

  14. Xiao, D., Liu, G.-B., Feng, W., Xu, X. & Yao, W. Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides. Phys. Rev. Lett. 108, 196802 (2012)

    Article  ADS  Google Scholar 

  15. Xu, X., Yao, W., Xiao, D. & Heinz, T. F. Spin and pseudospins in layered transition metal dichalcogenides. Nature Phys. 10, 343–350 (2014)

    Article  ADS  CAS  Google Scholar 

  16. Radisavljevic, B. & Kis, A. Mobility engineering and a metal-insulator transition in monolayer MoS2 . Nature Mater. 12, 815–820 (2013)

    Article  ADS  CAS  Google Scholar 

  17. Sundaram, R. S. et al. Electroluminescence in single layer MoS2 . Nano Lett. 13, 1416–1421 (2013)

    Article  ADS  CAS  Google Scholar 

  18. Baugher, B. W. H., Churchill, H. O. H., Yang, Y. & Jarillo-Herrero, P. Optoelectronic devices based on electrically tunable p-n diodes in a monolayer dichalcogenide. Nature Nanotechnol. 9, 262–267 (2014)

    Article  ADS  CAS  Google Scholar 

  19. Ross, J. S. et al. Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 p-n junctions. Nature Nanotechnol. 9, 268–272 (2014)

    Article  ADS  CAS  Google Scholar 

  20. Pospischil, A., Furchi, M. M. & Mueller, T. Solar-energy conversion and light emission in an atomic monolayer p-n diode. Nature Nanotechnol. 9, 257–261 (2014)

    Article  ADS  CAS  Google Scholar 

  21. Lopez-Sanchez, O., Lembke, D., Kayci, M., Radenovic, A. & Kis, A. Ultrasensitive photodetectors based on monolayer MoS2 . Nature Nanotechnol. 8, 497–501 (2013)

    Article  ADS  CAS  Google Scholar 

  22. Rivoire, K., Faraon, A. & Vuckovic, J. Gallium phosphide photonic crystal nanocavities in the visible. Appl. Phys. Lett. 93, 063103 (2008)

    Article  ADS  Google Scholar 

  23. Chalcraft, A. R. A. et al. Mode structure of the L3 photonic crystal cavity. Appl. Phys. Lett. 90, 241117 (2007)

    Article  ADS  Google Scholar 

  24. Gan, X. et al. Controlling the spontaneous emission rate of monolayer MoS2 in a photonic crystal nanocavity. Appl. Phys. Lett. 103, 181119 (2013)

    Article  ADS  Google Scholar 

  25. Wu, S. et al. Control of two-dimensional excitonic light emission via photonic crystal. 2D Mater. 1, 011001 (2014)

    Article  CAS  Google Scholar 

  26. Schwarz, S. et al. Two-dimensional metal-chalcogenide films in tunable optical microcavities. Nano Lett. 14, 7003–7008 (2014)

    Article  ADS  CAS  Google Scholar 

  27. Tanaka, Y., Asano, T., Akahane, Y., Song, B.-S. & Noda, S. Theoretical investigation of a two-dimensional photonic crystal slab with truncated cone air holes. Appl. Phys. Lett. 82, 1661–1663 (2003)

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  30. Liu, X., Galfsky, T., Sun, Z., Xia, F. & Lin, E. Strong light-matter coupling in two-dimensional atomic crystals. Preprint at (2014)

  31. Björk, G., Karlsson, A. & Yamamoto, Y. Definition of a laser threshold. Phys. Rev. A 50, 1675–1680 (1994)

    Article  ADS  Google Scholar 

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We thank C. Dodson for helping with reflection measurements of nanocavities. This work was mainly supported by AFOSR (FA9550-14-1-0277). A.M. is supported by NSF-EFRI-1433496. Photonic crystal fabrication was performed in part at the Stanford Nanofabrication Facility of NNIN supported by the NSF under grant no. ECS-9731293, and at the Stanford Nano Center. S.W. was partially supported by the State of Washington through the University of Washington Clean Energy Institute. S.B. and J.V. were supported by the Presidential Early Award for Scientists and Engineers (PECASE) administered through the Office of Naval Research, under grant number N00014-08-1-0561. S.B. was also supported by a Stanford Graduate Fellowship. J.Y. and D.G.M. were supported by US DoE, BES, Materials Sciences and Engineering Division. F.H. acknowledges support from the European Commission (FP7-ICT-2013-613024-GRASP).

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Authors and Affiliations



X.X. and A.M. conceived the experiments. S.B. and A.M. fabricated and characterized PCCs under the supervision of J.V. S.W. fabricated the hybrid devices and performed the measurements with assistance from J.R.S. and L.F., under the supervision of X.X. S.W., X.X., A.M. and S.B. analysed the data, and acknowledge discussions with W.Y. and J.V. J.Y. and D.G.M. provided the bulk WSe2. F.H. grew the GaP membrane. S.W. wrote the paper with input from all authors.

Corresponding authors

Correspondence to Arka Majumdar or Xiaodong Xu.

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The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Cavity Q-factor determination.

a, SEM image of a typical PCC. b, c, Room-temperature cross-polarized reflection taken from this cavity, before (b) and after (c) monolayer WSe2 transfer. As-fabricated cavities (before transfer) of our lasing devices typically have Q-factors ranging from 5,000 to 14,000. After monolayer transfer, the Q-factor is reduced from 8,000 to 1,300 in this device. After cooling down to cryogenic temperatures, the Q-factor recovers to 2500.

Extended Data Figure 2 Behaviour of device with Q-factor reduced by poly(methyl methacrylate).

a, Photoluminescence spectra taken from the PMMA covered device at different pumping powers (30 K), showing pronounced cavity peaks. b, Magnified view of cavity peaks ringed in a. c, Power dependence of the integrated peak intensity. A nonlinear ‘kink’ appears around 100 μW. The PMMA layer reduces the Q-factor to 500, and also shifts the resonance to lower energy (750.7 nm). This supports the conclusion that the ultralow lasing threshold in our device results from the high Q-factor, by significantly enhancing the spontaneous emission rate into the lasing mode.

Extended Data Figure 3 Nonlinear ‘kinks’ in plots of device properties at 80 K.

a, b, Plots show pump power dependence of integrated emission intensity (a) and line width (b). The same set of data are shown here as in Fig. 2b.

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Wu, S., Buckley, S., Schaibley, J. et al. Monolayer semiconductor nanocavity lasers with ultralow thresholds. Nature 520, 69–72 (2015).

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