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Active control of slow light on a chip with photonic crystal waveguides


It is known that light can be slowed down in dispersive materials near resonances1. Dramatic reduction of the light group velocity—and even bringing light pulses to a complete halt—has been demonstrated recently in various atomic2,3,4,5 and solid state systems6,7,8, where the material absorption is cancelled via quantum optical coherent effects3,4,5,7. Exploitation of slow light phenomena has potential for applications ranging from all-optical storage to all-optical switching9,10. Existing schemes, however, are restricted to the narrow frequency range of the material resonance, which limits the operation frequency, maximum data rate and storage capacity10. Moreover, the implementation of external lasers, low pressures and/or low temperatures prevents miniaturization and hinders practical applications. Here we experimentally demonstrate an over 300-fold reduction of the group velocity on a silicon chip via an ultra-compact photonic integrated circuit using low-loss silicon photonic crystal waveguides11,12 that can support an optical mode with a submicrometre cross-section13,14. In addition, we show fast (100 ns) and efficient (2 mW electric power) active control of the group velocity by localized heating of the photonic crystal waveguide with an integrated micro-heater.

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Figure 1: SEM images of a passive unbalanced Mach–Zehnder interferometer using photonic crystal waveguides.
Figure 2: Optical measurements of a passive unbalanced MZI.
Figure 3: Active electrically tunable MZI with lateral electrical contacts to photonic crystal waveguides.
Figure 4: Thermo-optic tuning of the group index in the active unbalanced MZI.


  1. Brillouin, L. Wave Propagation and Group Velocity (Academic, New York, 1960)

    MATH  Google Scholar 

  2. Hau, L. V. et al. Light speed reduction to 17 meters per second in an ultracold atomic gas. Nature 397, 594–598 (1999)

    Article  ADS  CAS  Google Scholar 

  3. Liu, C. et al. Observation of coherent optical information storage in an atomic medium using halted light pulses. Nature 409, 490–493 (2001)

    Article  ADS  CAS  Google Scholar 

  4. Bajcsy, M. et al. Stationary pulses of light in an atomic medium. Nature 426, 638–641 (2003)

    Article  ADS  CAS  Google Scholar 

  5. Lukin, M. D. & Imamoglu, A. Controlling photons using electromagnetically induced transparency. Nature 413, 273–276 (2001)

    Article  ADS  CAS  Google Scholar 

  6. Ku, P. C. et al. Slow light in semiconductor quantum wells. Opt. Lett. 29, 2291–2293 (2004)

    Article  ADS  CAS  Google Scholar 

  7. Turukhin, A. V. et al. Observation of ultraslow and stored light pulses in a solid. Phys. Rev. Lett. 88, 023602 (2002)

    Article  ADS  CAS  Google Scholar 

  8. Bigelow, M. S. et al. Superluminal and slow light propagation in a room-temperature solid. Science 301, 200–202 (2003)

    Article  ADS  CAS  Google Scholar 

  9. Mok, J. T. & Eggleton, B. J. Expect more delays. Nature 433, 811–812 (2005)

    Article  ADS  CAS  Google Scholar 

  10. Khurgin, J. B. Optical buffers based on slow light in electromagnetically induced transparent media and coupled resonator structures: comparative analysis. J. Opt. Soc. Am. B 22, 1062–1074 (2005)

    Article  ADS  CAS  Google Scholar 

  11. McNab, S. J., Moll, N. & Vlasov, Y. A. Ultra-low loss photonic integrated circuit with membrane-type photonic crystal waveguides. Opt. Express 11, 2927–2939 (2003)

    Article  ADS  Google Scholar 

  12. Dulkeith, E., McNab, S. J. & Vlasov, Y. A. Mapping the optical properties of slab-type two-dimensional photonic crystal waveguides. Phys. Rev. B 72, 115102 (2005)

    Article  ADS  Google Scholar 

  13. Krauss, T. F., De La Rue, R. & Brand, S. Two-dimensional photonic-bandgap structures operating at near-infrared wavelengths. Nature 383, 699–702 (1996)

    Article  ADS  CAS  Google Scholar 

  14. Notomi, M. et al. Extremely large group-velocity dispersion of line-defect waveguides in photonic crystal slabs. Phys. Rev. Lett. 87, 253902 (2001)

    Article  ADS  CAS  Google Scholar 

  15. Vlasov, Y. A. et al. Femtosecond measurements of the time of flight of photons in a three-dimensional photonic crystal. Phys. Rev. E 60, 1030–1035 (1999)

    Article  ADS  CAS  Google Scholar 

  16. Gersen, H. et al. Real-space observation of ultraslow light in photonic crystal waveguides. Phys. Rev. Lett. 94, 073903 (2005)

    Article  ADS  CAS  Google Scholar 

  17. Astratov, V. N. et al. Heavy photon dispersions in photonic crystal waveguides. Appl. Phys. Lett. 77, 178–180 (2000)

    Article  ADS  CAS  Google Scholar 

  18. Altug, H. & Vuckovic, J. Experimental demonstration of the slow group velocity of light in two-dimensional coupled photonic crystal microcavity arrays. Appl. Phys. Lett. 86, 111102 (2004)

    Article  ADS  Google Scholar 

  19. Vlasov, Y. A. & McNab, S. J. Coupling into the slow light mode in slab-type photonic crystal waveguides. Opt. Lett. (in the press); preprint at (2005).

  20. Johnson, S. G. & Joannopoulos, J. D. Block-iterative frequency-domain methods for Maxwell's equations in a planewave basis. Opt. Express 8, 173–190 (2001)

    Article  ADS  CAS  Google Scholar 

  21. Bendickson, J. M., Dowling, J. P. & Scalora, M. Analytic expressions for the electromagnetic mode density in finite, one-dimensional, photonic band-gap structures. Phys. Rev. E 53, 4107–4121 (1996)

    Article  ADS  CAS  Google Scholar 

  22. Cocorullo, G. & Rendina, I. Thermo-optical modulation at 1.5µm in silicon etalon. Electron. Lett. 28, 83–85 (1992)

    Article  Google Scholar 

  23. Geis, M. W., Spector, S. J., Williamson, R. C. & Lyszczarz, T. M. Submicrosecond submilliwatt silicon-on-insulator thermooptic switch. IEEE Photon. Technol. Lett. 16, 2514–2516 (2004)

    Article  ADS  CAS  Google Scholar 

  24. Espinola, R. L., Tsai, M.-C., Yardley, J. T. & Osgood, R. M. Fast and low-power thermooptic switch on thin silicon-on-insulator. IEEE Photon. Technol. Lett. 15, 1366–1368 (2003)

    Article  ADS  Google Scholar 

  25. Camargo, E. A., Chong, H. M. H. & De La Rue, R. M. 2D Photonic crystal thermo-optic switch based on AlGaAs/GaAs epitaxial structure. Opt. Express 12, 588–592 (2004)

    Article  ADS  Google Scholar 

  26. McNab, S. J., Hamann, H. F., Vlasov, Y. A. Lateral electrical contacts for photonic crystal based integrated opto-electronic devices. Pending US patent US20050084195A1 (15 October 2003).

  27. McNab, S. J., Hamann, H. F., O'Boyle, M. & Vlasov, Y. A. Method and apparatus for thermo-optic modulation of optical signals. Pending US patent, US20050084213A1 (12 January 2004).

  28. Vlasov, Y. A. & McNab, S. J. Losses in single-mode silicon-on-insulator strip waveguides and bends. Opt. Express 12, 1622–1631 (2004)

    Article  ADS  Google Scholar 

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This work was partially supported by the DARPA DSO Slow Light programme.

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Correspondence to Yurii A. Vlasov.

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Supplementary information

Supplementary Methods

Description of process flow and schematic for fabricating the active Mach Zehnder Interferometer. (PDF 291 kb)

Supplementary Discussion

Limitations of the interferometric method for extracting the group indices from the transmission spectra of the Mach-Zehnder Interferometer. (PDF 12 kb)

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Vlasov, Y., O'Boyle, M., Hamann, H. et al. Active control of slow light on a chip with photonic crystal waveguides. Nature 438, 65–69 (2005).

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