Strained silicon as a new electro-optic material

Abstract

For decades, silicon has been the material of choice for mass fabrication of electronics. This is in contrast to photonics, where passive optical components in silicon have only recently been realized1,2. The slow progress within silicon optoelectronics, where electronic and optical functionalities can be integrated into monolithic components based on the versatile silicon platform, is due to the limited active optical properties of silicon3. Recently, however, a continuous-wave Raman silicon laser was demonstrated4; if an effective modulator could also be realized in silicon, data processing and transmission could potentially be performed by all-silicon electronic and optical components. Here we have discovered that a significant linear electro-optic effect is induced in silicon by breaking the crystal symmetry. The symmetry is broken by depositing a straining layer on top of a silicon waveguide, and the induced nonlinear coefficient, χ(2) ≈ 15 pm V-1, makes it possible to realize a silicon electro-optic modulator. The strain-induced linear electro-optic effect may be used to remove a bottleneck5 in modern computers by replacing the electronic bus with a much faster optical alternative.

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Figure 1: Applying strain to crystalline silicon.
Figure 2: Diagram of a Mach–Zehnder modulator.
Figure 3: Effect of straining the silicon structure.
Figure 4: Experimental verification of the linear enhancement of with the group index.

References

  1. 1

    Trinh, P. D., Yegnanarayanan, S., Coppinger, F. & Jalali, B. Silicon-on-insulator (SOI) phased-array wavelength multi/demultiplexer with extremely low-polarization sensitivity. IEEE Photon. Technol. Lett. 9, 940–942 (1997)

    ADS  Article  Google Scholar 

  2. 2

    Pavesi, L. & Lockwood, D. J. Silicon Photonics (Springer, Berlin, 2004)

    Google Scholar 

  3. 3

    Reed, G. T. & Png, C. E. J. Silicon optical modulators. Mater. Today 8, 40–50 (2005)

    CAS  Article  Google Scholar 

  4. 4

    Rong, H. et al. A continuous-wave Raman silicon laser. Nature 433, 725–727 (2005)

    ADS  CAS  Article  PubMed  Google Scholar 

  5. 5

    Gibbs, W. W. A split at the core. Sci. Am. 291, 96–100 (2004)

    ADS  Article  PubMed  Google Scholar 

  6. 6

    Madou, M. J. Fundamentals of Microfabrication 299–301 (CRC Press, Boca Raton, Florida, 2002)

    Google Scholar 

  7. 7

    Li, G. L. & Yu, P. K. L. Optical intensity modulators for digital and analog applications. J. Lightwave Technol. 21, 2010–2030 (2003)

    ADS  Article  Google Scholar 

  8. 8

    Butcher, P. N. & Cotter, D. The Elements of Nonlinear Optics 5 (Cambridge Univ. Press, Cambridge, UK, 1990)

    Google Scholar 

  9. 9

    Soljacic, M. & Joannopoulos, J. D. Enhancement of nonlinear effects using photonic crystals. Nature Mater. 3, 211–219 (2004)

    ADS  CAS  Article  Google Scholar 

  10. 10

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

    ADS  CAS  Article  PubMed  Google Scholar 

  11. 11

    Joannopoulos, J. D., Villeneuve, P. R. & Fan, S. Photonic crystals: putting a new twist on light. Nature 386, 143–149 (1997)

    ADS  CAS  Article  Google Scholar 

  12. 12

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

    ADS  CAS  Article  Google Scholar 

  13. 13

    Joannopoulos, J. D., Meade, R. D. & Winn, J. N. Photonic Crystals: Molding the Flow of Light (Princeton Univ. Press, Princeton, 1995)

    Google Scholar 

  14. 14

    Jacobsen, R. S. et al. Direct experimental and numerical determination of extremely high group indices in photonic crystal waveguides. Opt. Express 13, 7861–7871 (2005)

    ADS  Article  PubMed  Google Scholar 

  15. 15

    Hitoshi, N. et al. Ultra-fast photonic crystal/quantum dot all-optical switch for future photonic networks. Opt. Express 12, 6606–6614 (2004)

    Article  PubMed  Google Scholar 

  16. 16

    Soref, R. A. Silicon-based optoelectronics. Proc. IEEE 81, 1687–1706 (1993)

    CAS  Article  Google Scholar 

  17. 17

    Myers, R. A., Mukherhee, N. & Brueck, S. R. J. Large second-order nonlinearity in poled fused silica. Opt. Lett. 16, 1732–1734 (1991)

    ADS  CAS  Article  PubMed  Google Scholar 

  18. 18

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

    ADS  Article  PubMed  Google Scholar 

  19. 19

    Kondo, J. et al. 40-Gb/s X-cut LiNbO3 optical modulator with two-step back-slot structure. J. Lightwave Technol. 20, 2110–2114 (2002)

    ADS  Article  Google Scholar 

  20. 20

    Liao, W. J. et al. Proton-exchanged optical waveguides fabricated by glutaric acid. Opt. Laser Technol. 36, 603–606 (2004)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Lee, K. K., Lim, D. R., Kimerling, L. C., Shin, J. & Cerrina, F. Fabrication of ultralow-loss Si/SiO2 waveguides by roughness reduction. Opt. Lett. 26, 1888–1890 (2001)

    ADS  CAS  Article  PubMed  Google Scholar 

  22. 22

    Soref, R. A. & Bennett, B. R. Electrooptical effects in silicon. IEEE J. Quant. Electron. QE-23, 123–129 (1987)

    ADS  CAS  Article  Google Scholar 

  23. 23

    Liu, A. et al. A high-speed silicon optical modulator based on a metal-oxide-semiconductor capacitor. Nature 427, 615–618 (2004)

    ADS  CAS  Article  PubMed  Google Scholar 

  24. 24

    Liao, L. et al. High speed silicon Mach-Zehnder modulator. Opt. Express 13, 3129–3135 (2005)

    ADS  CAS  Article  PubMed  Google Scholar 

  25. 25

    Bogaerts, W. et al. Nanophotonic waveguides in silicon-on-insulator fabricated with CMOS technology. J. Lightwave Technol. 23, 401–412 (2005)

    ADS  CAS  Article  Google Scholar 

  26. 26

    Rasmussen, F. E. Electrical Interconnections through CMOS Wafers. PhD. thesis, Tech. Univ. Denmark (2003); http://www.mic.dtu.dk/upload/institutter/mic/forskning/mems/report-31102003.pdf

    Google Scholar 

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Acknowledgements

We thank R. Kjær and M. Svalgaard for their contributions. This work was supported in part by the NKT academy, the Danish Research Council for Technology and Production Sciences via the PIPE project, by NEDO via the Industrial Technology Research Area and by CINF via the Danish National Research Foundation. All generic SOI PCWs were fabricated within the framework of the European IST project PICCO and in this connection we especially thank W. Bogaerts and R. Baets.

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Correspondence to Rune S. Jacobsen.

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Jacobsen, R., Andersen, K., Borel, P. et al. Strained silicon as a new electro-optic material. Nature 441, 199–202 (2006). https://doi.org/10.1038/nature04706

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