Electrically driven subwavelength optical nanocircuits

Journal name:
Nature Photonics
Year published:
Published online


The miniaturization of electronic and photonic device technologies has facilitated information processing and transport at ever-increasing speeds and decreasing power levels. Nanometallics or ‘plasmonics’ has empowered us to break the diffraction limit and open the door to the development of truly nanoscale optical circuits. A logical next step in this development is the realization of compact optical sources capable of electrically driving such nanocircuits. Nanometallic lasers are a possible candidate, but the realization of power-efficient, electrically pumped nanolasers at room temperature is extremely challenging. Here, we explore a plasmonic light-emitting diode as a possible alternative option. We demonstrate that an electrically driven, nano light-emitting diode is capable of directing light emission into a single-mode plasmon waveguide with a cross-sectional area of 0.016λ2 by exploiting the Purcell effect. With this source, electrically driven subwavelength optical nanocircuits for routing, splitting, free-space coupling and directional coupling are realized for the first time.

At a glance


  1. Subwavelength slot-waveguide-coupled nano-LED platform.
    Figure 1: Subwavelength slot-waveguide-coupled nano-LED platform.

    a, Schematic showing an integrated, electrically driven optical nanocircuit composed of three-dimensional slot-waveguide components, including two ultracompact splitters, a directional coupler and slot antennas. b, SEM image of a fabricated nano-LED coupled to a slot-waveguide-based T-splitter. Red and blue dashed lines indicate the position for the FIB milled cross-sections in c and d. c, The nano-LED, with the quantum well located between the two red arrows. d, A suspended slot waveguide generated by FIB milling and under-etching of the GaAs substrate. e, Mode profile of an 80-nm-wide and 150-nm-tall slot waveguide.

  2. Optical characterization of the nano-LED source.
    Figure 2: Optical characterization of the nano-LED source.

    a, Electroluminescence emission map overlaid on an SEM image of a 2.5-μm-long nano-LED fabricated on an oxidized AlGaAs substrate. A single light output spot is observed in the gap between the p- and n-contacts. b, SEM image and electroluminescence image overlay of a nano-LED coupled to 5 µm slot waveguide. The collected electroluminescence with x-polarized detection shows a scattering spot at the end of the nano-LED-driven slot waveguide, consistent with the behaviour of gap plasmon guiding and outcoupling. c, Electroluminescence intensity spectrum collected from the device shown in a (red line) and the simulation predicted spectrum (black line). The red arrows indicate the positions of the Fabry-Pérot resonance wavelengths determined from the one-dimensional cavity model. The orange arrow indicates the emission from the GaAs barrier.

  3. Slot waveguide-based T-splitter and slot antennas.
    Figure 3: Slot waveguide-based T-splitter and slot antennas.

    a, Optical image of a T-splitter-coupled nano-LED fabricated on a GaAs substrate. The black dashed rectangle outlines the region shown in e and f. b, Simulated electric field intensity for gap plasmon splitting at a T-junction. c, Top view of the simulated electric field intensity for a 320-nm-long, waveguide-fed slot antenna. d, Side view of the simulated electric field intensity for the waveguide-fed slot antenna across the yellow dashed line in c, showing free-space radiation. e, Electroluminescence scattering image with y-polarized detection overlaid on top of the SEM image of the device. f, Electroluminescence scattering image with x-polarized detection overlaid on top of the SEM image of the device.

  4. Slot-waveguide-based directional coupler.
    Figure 4: Slot-waveguide-based directional coupler.

    a, Simulation of the coupling efficiency to each directional coupler output port as a function of the centre-to-centre separation d between two waveguides. Inset: simulated electric field intensity for a directional coupler with d = 160 nm. Gap plasmons are injected from the input port (white arrow), and can be reflected (red arrow), coupled (blue arrow) or transmitted (orange arrow). b, Electroluminescence scattering image with y-polarized detection overlaid on top of the device SEM image, showing emission from the coupled port. c, Electroluminescence scattering image with x-polarization sensitive detection overlaid on the device SEM image, showing no detectable scattering signal from the transmission port.


  1. Gramotnev, D. K. & Bozhevolnyi S. Plasmonics beyond the diffraction limit. Nature Photon. 4, 8391 (2010).
  2. Papaioannou, S. et al. A 320 Gb/s throughput 2 × 2 silicon-plasmonic router architecture for optical interconnects. J. Lightwave Technol. 29, 31853195 (2011)
  3. De Leon, N. P., Lukin, M. D. & Park, H. Quantum plasmonic circuits. IEEE J. Quantum Electron. 18, 17811791 (2012).
  4. Anker, J. N. et al. Biosensing with plasmonic nanosensors. Nature Mater. 7, 442453 (2008).
  5. Service, R. F. Ever-smaller lasers pave the way for data highways made of light. Science 328, 810811 (2010).
  6. Noda, S. Seeking the ultimate nanolaser. Science 314, 260261 (2006).
  7. Khajavikhan, M. et al. Thresholdless nanoscale coaxial lasers. Nature 482, 204207 (2012).
  8. Hill, M. T. et al. Lasing in metallic-coated nanocavities. Nature Photon. 1, 589594 (2007).
  9. Marell, M. J. H. et al. Plasmonic distributed feedback lasers at telecommunications wavelengths. Opt. Express 19, 1510915118 (2011).
  10. Kwon, S.-H. et al. Subwavelength plasmonic lasing from a semiconductor nanodisk with silver nanopan cavity. Nano Lett. 10, 36793683 (2010).
  11. Noginov, M. A. et al. Demonstration of a spaser-based nanolaser. Nature 460, 11101112 (2009).
  12. Oulton, R. F. et al. Plasmon lasers at deep subwavelength scale. Nature 461, 629632 (2009).
  13. Yu, K., Lakhani, A. & Wu, M. C. Subwavelength metal-optic semiconductor nanopatch lasers. Opt. Express 18, 87908799 (2010).
  14. Nezhad, M. P. et al. Room-temperature subwavelength metallo-dielectric lasers. Nature Photon. 4, 395399 (2010).
  15. Chen, R. et al. Nanolasers grown on silicon. Nature Photon. 5, 170175 (2011).
  16. Ellis, B. et al. Ultralow-threshold electrically pumped quantum-dot photonic-crystal nanocavity laser. Nature Photon. 5, 297300 (2011).
  17. Loncar, M., Yoshie, T., Scherer, A., Gogna, P. & Qiu, Y. Low-threshold photonic crystal laser. Appl. Phys. Lett. 81, 26802682 (2002).
  18. Noda, S. Photonic crystal lasers—ultimate nanolasers and broad-area coherent lasers. J. Opt. Soc. Am. B 27, B1B8 (2010).
  19. Khurgin, J. B. & Sun, G. Injection pumped single mode surface plasmon injection pumped single mode surface plasmon generators: threshold, linewidth, and coherence. Opt. Express 20, 1530915325 (2012).
  20. Khurgin, J. B. & Sun, G. How small can ‘Nano’ be in a ‘Nanolaser’? Nanophotonics 1, 38 (2012).
  21. Okamoto, K. et al. Surface-plasmon-enhanced light emitters based on InGaN quantum wells. Nature Mater. 3, 601605 (2004).
  22. Koller, D. M. et al. Organic plasmon-emitting diode. Nature Photon. 2, 684687 (2008).
  23. Walters, R. J., van Loon, R. V. A., Brunets, I., Schmitz, J. & Polman, A. A silicon-based electrical source of surface plasmon polaritons. Nature Mater. 9, 2125 (2010).
  24. Neutens, P., Lagae, L., Borghs, G. & Van Dorpe, P. Electrical excitation of conned surface plasmon polaritons in metallic slot waveguides. Nano Lett. 10, 14291432 (2010).
  25. Veronis, G. & Fan, S. Theoretical investigation of compact couplers between dielectric slab waveguides and two-dimensional metal–dielectric–metal plasmonic waveguides. Opt. Express 15, 12111221 (2007).
  26. Brongersma, M. L. et al. in Plasmonic Nanoguides and Circuits (ed. Bozhevolnyi, S.) Ch. 13 (Pan Stanford, 2008).
  27. Cai, W., Shin, W., Fan, S. & Brongersma, M. L. Elements for plasmonic nanocircuits with three-dimensional slot waveguides. Adv. Mater. 22, 51205124 (2010).
  28. Veronis, G. & Fan, S. Modes of subwavelength plasmonic slot waveguides. J. Lightwave Technol. 25, 25112521 (2007).
  29. Kurokawa, Y. & Miyazaki, H. T. Metal–insulator–metal plasmon nanocavities: analysis of optical properties. Phys. Rev. B 75, 035411 (2007).
  30. Pile, D. F. P. & Gramotnev, D. Plasmonic subwavelength waveguides: next to zero losses at sharp bends. Opt. Lett. 30, 11861188 (2005).
  31. Pile, D. F. P. et al. Two-dimensionally localized modes of a nanoscale gap plasmon waveguide. Appl. Phys. Lett. 87, 261114 (2005).
  32. Pile, D. F. P., Gramotnev, G. K., Rupert, O. F. & Zhang, X. On long-range plasmonic modes in metallic gaps. Opt. Express 15, 1366913674 (2007).
  33. Pile, D. F. P. & Gramotnev, G. K. Channel plasmon–polariton in a triangular groove on a metal surface. Opt. Lett. 29, 10691071 (2004).
  34. Jun, Y. C., Kekatpure, R. D., White, J. S. & Brongersma, M. L. Nonresonant enhancement of spontaneous emission in metal–dielectric–metal plasmon waveguide structures. Phys. Rev. B 78, 153111 (2008).
  35. Jun, Y. C., Huang, K. C. Y. & Brongersma, M. L. Plasmonic beaming and active control over uorescent emission. Nature Commun. 2, 283 (2011).
  36. Lau, E. K., Lakhani, A., Tucker, R. S. & Wu, M. C. Enhanced modulation bandwidth of nanocavity light emitting devices. Opt. Express 17, 77907799 (2009).
  37. Shambat, G. et al. Ultrafast direct modulation of a single-mode photonic crystal nanocavity light-emitting diode. Nature Commun. 2, 539 (2011).
  38. Suhr, T., Gregersen, N., Yvind, K. & Mork, J. Modulation response of nanoLEDs and nanolasers exploiting Purcell enhanced spontaneous emission. Opt. Express 18, 1123011241 (2010).
  39. Chen, C. et al. GHz bandwidth GaAs light-emitting diodes. Appl. Phys. Lett. 74, 31403142 (1999).
  40. Fattal, D. et al. Design of an efcient light-emitting diode with 10 GHz modulation bandwidth. Appl. Phys. Lett. 93, 243501 (2008).
  41. Walter, G., Wu, C. H., Then, H. W., Feng, M. & Holonyak, N. Jr. Tilted-charge high speed (7 GHz) light emitting diode. Appl. Phys. Lett. 94, 231125 (2009).
  42. Miller, D. A. B. Device requirements for optical interconnects to silicon chips. Proc. IEEE 97, 11661185 (2009).
  43. Palik, E. D. Handbook of Optical Constants of Solids (Academic, 1985).
  44. Bozhevolnyi, S., Volkov, V., Devaux, E., Laluet, J. & Ebbesen, T. Channel plasmon sub-wavelength waveguide components including interferometers and ring resonators. Nature 440, 508511 (2006).
  45. Zablocki, M. J., Sharkawy, A., Ebil, O., Shi, S. & Prather, D. Electro-optically switched compact coupled photonic crystal waveguide directional coupler. Appl. Phys. Lett. 96, 081110 (2010).
  46. Zenin, V. A. et al. Directional coupling in channel plasmon–polariton waveguides. Opt. Express 20, 61246134 (2012).
  47. Haus, H. A. Waves and Fields in Optoelectronics (Prentice-Hall, 1984).
  48. Chen, L., Shakya, J. & Lipson, M. Subwavelength connement in an integrated metal slot waveguide on silicon. Opt. Lett. 31, 21332135 (2006).
  49. Hryciw, A., Jun. Y. C. & Brongersma, M. L. Electrifying plasmonics on silicon. Nature Mater. 9, 34 (2010).
  50. Taove, A. & Hagness, S. C. Computational Electrodynamics: The Finite-Difference Time-Domain Method 3rd edn (Artech House, 2005).

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Author information

  1. These authors contributed equally to this work

    • Kevin C. Y. Huang &
    • Min-Kyo Seo


  1. Geballe Laboratory for Advanced Materials, Stanford University, McCullough Building, 476 Lomita Mall, Stanford, California 94305-4045, USA

    • Kevin C. Y. Huang,
    • Min-Kyo Seo &
    • Mark L. Brongersma
  2. Department of Electrical Engineering, Stanford University, David Packard Building, 350 Serra Mall, Stanford, California 94305-9505, USA

    • Kevin C. Y. Huang,
    • Tomas Sarmiento,
    • Yijie Huo &
    • James S. Harris
  3. Department of Physics and Institute for the NanoCentury, KAIST, Daejeon 305-701, South Korea

    • Min-Kyo Seo


M.-K.S. and M.L.B. conceived the idea. K.C.Y.H. and M.-K.S. designed the structures. Y.H. and T.S. performed the molecular beam epitaxial growth of the quantum-well structure under the supervision of J.S.H. K.C.Y.H. and M.-K.S. performed theoretical calculations and full-eld simulations. K.C.Y.H. and M.-K.S. fabricated and characterized the samples. K.C.Y.H. and M.L.B. wrote the manuscript. M.L.B. supervised the project.

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