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Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer

A Retraction to this article was published on 08 March 2013

Abstract

An efficient, room-temperature-operation continuous-wave terahertz source will greatly benefit compact terahertz system development for high-resolution terahertz spectroscopy and imaging applications. Here, we report highly efficient continuous-wave terahertz emission using nanogap electrodes in a photoconductive antenna-based photomixer. The tip-to-tip nanogap electrode structure provides strong terahertz field enhancement and acts as a nano-antenna to radiate the terahertz wave generated in the active region of the photomixer. In addition, it provides good impedance-matching to the terahertz planar antenna and exhibits a lower RC time constant, allowing more efficient radiation, especially at the higher part of the terahertz spectrum. As a result, the output power of the photomixer with the new nanogap electrode structure in the active region is two orders of magnitude higher than for a photomixer with typical interdigitated electrodes. The terahertz emission bandwidth also increases by a factor of more than two.

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Figure 1: Schematic drawings of the fabricated c.w. terahertz photomixers.
Figure 2: Plan-view SEM images of the c.w. terahertz photomixers.
Figure 3: Terahertz output characteristics of the photomixers.
Figure 4: Electric field amplitude in the near field of a modified meander antenna with different photomixers at 1 THz plane-wave illumination.
Figure 5: FDTD simulation of electric field enhancement as a function of gap width and simulation of field intensity distributions within the active region under 1 THz plane-wave illumination.

References

  1. Winnewisser, G. Spectroscopy in the terahertz region. Vibrat. Spectrosc. 8, 241–253 (1995).

    Article  Google Scholar 

  2. Siegel, P. H. Terahertz technology. IEEE Trans. Microw. Theory Tech. 50, 910–928 (2002).

    ADS  Article  Google Scholar 

  3. Hu, B. B. & Nuss, M. C. Imaging with terahertz waves. Opt. Lett. 20, 1716–1718 (1995).

    ADS  Article  Google Scholar 

  4. Shen, Y. C. et al. Detection and identification of explosives using terahertz pulsed spectroscopic imaging. Appl. Phys. Lett. 86, 241116 (2005).

    ADS  Article  Google Scholar 

  5. Tonouchi, M. Cutting-edge terahertz technology. Nature Photon. 1, 97–105 (2007).

    ADS  Article  Google Scholar 

  6. Williams, B. S. Terahertz quantum-cascade lasers. Nature Photon. 1, 517–525 (2007).

    ADS  Article  Google Scholar 

  7. Qin, Q., Williams, B. S., Kumar, S., Hu, Q. & Reno, J. L. Tuning a terahertz wire laser. Nature Photon. 3, 732–737 (2009).

    ADS  Article  Google Scholar 

  8. Amanti, M. I., Fischer, M., Scalari, G., Beck, M. & Faist, J. Low-divergence single-mode terahertz quantum cascade laser. Nature Photon. 3, 586–590 (2009).

    ADS  Article  Google Scholar 

  9. Kumar, S. Chan, C. W. I., Hu, Q. & Reno, J. L. A 1.8-THz quantum cascade laser operating significantly above the temperature of ħω/kB . Nature Phys. 7, 166–171 (2011).

    ADS  Article  Google Scholar 

  10. Maineult, W. et al. Metal–metal terahertz quantum cascade laser with micro-transverse-electromagnetic-horn antenna. Appl. Phys. Lett. 93, 183508 (2008).

    ADS  Article  Google Scholar 

  11. Kumar, S., Hu, Q. & Reno, J. L. 186 K operation of terahertz quantum-cascade lasers based on a diagonal design. Appl. Phys. Lett. 94, 131105 (2009).

    ADS  Article  Google Scholar 

  12. Ferguson, B. & Zhang, X. C. Materials for terahertz science and technology. Nature Mater. 1, 26–33 (2002).

    ADS  Article  Google Scholar 

  13. Preu, S., Döhler, G. H., Malzer, S., Wang, L. J. & Gossard, A. C. Tunable, continuous-wave terahertz photomixer sources and applications. J. Appl. Phys. 109, 061301 (2011).

    ADS  Article  Google Scholar 

  14. McIntosh, K. A. et al. Terahertz photomixing with diode lasers in low-temperature-grown GaAs. Appl. Phys. Lett. 67, 3844–3846 (1995).

    ADS  Article  Google Scholar 

  15. Gregory, I. S. et al. Resonant dipole antennas for continuous-wave terahertz photomixers. Appl. Phys. Lett. 85, 1622–1624 (2004).

    ADS  Article  Google Scholar 

  16. Brown, E. R., McIntosh, K. A., Nichols, K. B. & Dennis, C. L. Photomixing up to 3.8 THz in low-temperature-grown GaAs. Appl. Phys. Lett. 66, 285–287 (1995).

    ADS  Article  Google Scholar 

  17. Brown, E. R. THz generation by photomixing in ultrafast photoconductors. Int. J. High Speed Electron. Syst. 13, 497–545 (2003).

    Article  Google Scholar 

  18. Gregory, I. S. et al. Optimization of photomixers and antennas for continuous-wave terahertz emission. IEEE J. Quant. Electron. 41, 717–728 (2005).

    ADS  Article  Google Scholar 

  19. Duffy, S. M. et al. Accurate modeling of dual dipole and slot elements used with photomixers for coherent terahertz output power. IEEE Trans. Microwave Theor. Tech. 49, 1032–1038 (2001).

    ADS  Article  Google Scholar 

  20. Mangeney, J. et al. Continuous wave terahertz generation up to 2 THz by photomixing on ion-irradiated In0.53Ga0.47As at 1.55 µm wavelengths. Appl. Phys. Lett. 91, 241102 (2007).

    ADS  Article  Google Scholar 

  21. Samir, R. et al. Enhanced terahertz emission from a multilayered low temperature grown GaAs structure. Appl. Phys. Lett. 96, 091101 (2010).

    ADS  Article  Google Scholar 

  22. Sartorius, B. et al. Continuous wave terahertz systems exploiting 1.5 µm telecom technologies. Opt. Express 17, 15001–15007 (2009).

    ADS  Article  Google Scholar 

  23. Mikulics, M., Marso, M., Lepsa, M., Grützmacher, D. & Kordo, P. Output power improvement in MSM photomixers by modified finger contacts configuration. IEEE Photon. Tech. Lett. 21, 146–148 (2009).

    ADS  Article  Google Scholar 

  24. Pendry, J. B., Martin-Moreno, L. & Garcia-Vidal, F. J. Mimicking surface plasmons with structured surfaces. Science 305, 847–848 (2004).

    ADS  Article  Google Scholar 

  25. Williams, C. R. et al. Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces. Nature Photon. 2, 175–179 (2008).

    ADS  Article  Google Scholar 

  26. Williams, C. R. et al. Dual band terahertz waveguiding on a planar metal surface patterned with annular holes. Appl. Phys. Lett. 96, 011101 (2010).

    ADS  Article  Google Scholar 

  27. Chen, H. T. et al. Experimental demonstration of frequency-agile terahertz metamaterials. Nature Photon. 2, 295–298 (2008).

    Article  Google Scholar 

  28. Chen, H. T. et al. A metamaterial solid-state terahertz phase modulator. Nature Photon. 3, 148–151 (2009).

    ADS  Article  Google Scholar 

  29. Landy, N. I., Sajuyigbe, S., Mock, J. J., Smith, D. R. & Padilla, W. J. Perfect metamaterial absorber. Phys. Rev. Lett. 100, 207402 (2008).

    ADS  Article  Google Scholar 

  30. Yu, N. et al. Designer spoof surface plasmon structures collimate terahertz laser beams. Nature Mater. 9, 730–735 (2010).

    ADS  Article  Google Scholar 

  31. Seo, M. A. et al. Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit. Nature Photon. 3, 152–156 (2009).

    ADS  Article  Google Scholar 

  32. Novotny, L. & Hecht, B. Principles of Nano-optics (Cambridge Univ. Press, 2007).

  33. Kawano, Y. & Ishibashi, K. An on-chip near-field terahertz probe and detector. Nature Photon. 2, 618–621 (2008).

    Article  Google Scholar 

  34. Chen, H-T. et al. Active terahertz metamaterials devices. Nature 444, 597–600 (2006).

    ADS  Article  Google Scholar 

  35. Large, N., Abb, M., Aizpurua, J. & Muskens, O. L. Photoconductively loaded plasmonic nanoantenna as building block for ultracompact optical switches. Nano Lett. 10, 1741–1746 (2010).

    ADS  Article  Google Scholar 

  36. Mühlschlegel, P., Eisler, H. J., Martin, O. J., Hecht, B. & Pohl, D. W. Resonant optical antennas. Science 308, 1607–1609 (2005).

    ADS  Article  Google Scholar 

  37. Orton, J. The story of Semiconductors (Oxford Univ. Press, 2004).

  38. Widger, W. K. Jr & Woodall, M. P. Integration of the Planck blackbody radiation function. Bull. Am. Meteorol. Soc. 57, 1217–1219 (1976).

    ADS  Article  Google Scholar 

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Acknowledgements

H.T. and J.H.T. thank M. Tonouchi for helpful discussions. This work is financially supported by the Agency for Science, Technology and Research (A*STAR), Singapore (grant nos 082 1410038, 092 1540097 and 092 1540098) and by the Leverhulme Trust (UK).

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Contributions

J.H.T. conceived the idea and supervised the project. H.T. and Q.Y.W. contributed to the fabrication and characterization of the c.w. terahertz photomixer. M.S., Z.N.C., S.A.M. and B.W. contributed to the theory and simulation. H.T. and S.J.C. contributed to the wafer growth. C.C.C., S.G.Y. and A.J.D. contributed to the nanofabrications. H.T., J.H.T., B.W., M.S. and S.A.M. contributed to writing the manuscript. All authors discussed the results and contributed to the article.

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Correspondence to J. H. Teng.

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Tanoto, H., Teng, J., Wu, Q. et al. Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer. Nature Photon 6, 121–126 (2012). https://doi.org/10.1038/nphoton.2011.322

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