Field enhancement within an optical fibre with a subwavelength air core

Abstract

Tightly confined light enables a variety of applications ranging from nonlinear light management to atomic manipulation. Photonic-crystal fibres (PCFs) can provide strong guidance in very small cores while simultaneously offering long interaction lengths1. However, light confinement in waveguides is usually ultimately limited by diffraction2,3, which tends to spread light away from the waveguiding core, despite its higher refractive index. It was recently demonstrated that such spreading fields can be trapped by a nanometre-scale slot inside a strongly guiding silicon-on-insulator (SOI) waveguide4,5. In this letter we demonstrate the concentration of optical energy within a subwavelength-scale air hole running down the length of a PCF core. The core resembles a submicrometre-diameter tube with a bore diameter of 200 nm or less. The high intensity in an air hole, coupled with long interaction lengths, promises a new class of experiments in light–matter interaction and nonlinear fibre optics.

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Figure 1: SEM images from the fabricated PCF cross-sections.
Figure 2: Optical fields and figure of merit.
Figure 3: Group velocity dispersion of the fibres shown in Fig. 1.
Figure 4: Near-field mode patterns for PCF 3.

References

  1. 1

    Knight, J. C. Photonic crystal fibers. Nature 424, 847–851 (2003).

    ADS  Article  Google Scholar 

  2. 2

    Foster, M. A., Moll, K. D. & Gaeta, A. L. Optimal waveguide dimensions for nonlinear interactions. Opt. Express 12, 2880–2887 (2004).

    ADS  Article  Google Scholar 

  3. 3

    Zheltikov, A. M. The physical limit for the waveguide enhancement of nonlinear-optical processes. Opt. Spectrosc. 95, 410–415 (2003).

    ADS  Article  Google Scholar 

  4. 4

    Xu, Q. F., Almeida, V. R., Panepucci, R. R. & Lipson, M. Experimental demonstration of guiding and confining light in nanometer-size low-refractive-index material. Opt. Lett. 29, 1626–1628 (2004).

    ADS  Article  Google Scholar 

  5. 5

    Almeida, V. R., Xu, Q. F., Barrios, C. A. & Lipson, M. Guiding and confining light in void nanostructure. Opt. Lett. 29, 1209–1211 (2004).

    ADS  Article  Google Scholar 

  6. 6

    Baehr-Jones, T., Hochberg, M., Walker, C. & Scherer, A. High-Q optical resonators in silicon-on-insulator-based slot waveguides. Appl. Phys. Lett. 86, 081101 (2005).

    ADS  Article  Google Scholar 

  7. 7

    Roberts, P. et al. Ultimate low loss of hollow-core photonic crystal fibres. Opt. Express 13, 236–244 (2005).

    ADS  Article  Google Scholar 

  8. 8

    Benabid, F., Knight, J. C., Antonopoulos, G. & Russell, P. S. J. Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber. Science 298, 399–402 (2002).

    ADS  Article  Google Scholar 

  9. 9

    Saitoh, K., Florous, N. & Koshiba, M. Ultra-flattened chromatic dispersion controllability using a defected-core photonic crystal fiber with low confinement losses. Opt. Express 13, 8365–8371 (2005).

    ADS  Article  Google Scholar 

  10. 10

    Ito, H., Sakaki, K., Nakata, T., Jhe, W. & Ohtsu, M. Optical-potential for atom guidance in a cylindrical-core hollow-fiber. Opt. Commun. 115, 57–64 (1995).

    ADS  Article  Google Scholar 

  11. 11

    Vahala, K. J. Optical microcavities. Nature 424, 839–845 (2003).

    ADS  Article  Google Scholar 

  12. 12

    Nazarkin, A., Korn, G., Wittmann, M. & Elsaesser, T. Group-velocity-matched interactions in hollow waveguides: Enhanced high-order Raman scattering by impulsively excited molecular vibrations. Phys. Rev. A. 65, 041802 (2000).

    ADS  Article  Google Scholar 

  13. 13

    Koshiba, M. & Tsuji, Y. Curvilinear hybrid edge/nodal elements with triangular shape for guided-wave problems. J. Lightwave Technol. 18, 737–743 (2000).

    ADS  Article  Google Scholar 

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Acknowledgements

The authors would like to acknowledge help from A. George in fabricating the fibres and assistance from A. Frasson and H.E.H. Figueroa in the numerical simulations. G.S.W. and C.M.B.C. acknowledge financial support of the National Council for Scientific and Technological Development (CNPq) and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP). Work at Bath was funded by the UK Engineering and Physical Sciences Research Council.

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Correspondence to G. S. Wiederhecker.

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Wiederhecker, G., Cordeiro, C., Couny, F. et al. Field enhancement within an optical fibre with a subwavelength air core. Nature Photon 1, 115–118 (2007). https://doi.org/10.1038/nphoton.2006.81

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