Fano resonances and electromagnetically induced transparency in silicon waveguides loaded with plasmonic nanoresonators

The fundamental electric dipolar resonance of metallic nanostrips placed on top of a dielectric waveguide can be excited via evanescent wave coupling, thus giving rise to broad dips in the transmission spectrum of the waveguide. Here we show via numerical simulations that narrower and steeper Fano-like resonances can be obtained by asymmetrically coupling in the near field a larger nanostrip supporting an electric quadrupole in the frequency regime of interest to the original, shorter nanostrip. Under certain conditions, the spectral response corresponding to the electromagnetically induced transparency phenomenon is observed. We suggest that this hybrid plasmonic photonic approach could be especially relevant for sensing or all-optical switching applications in a photonic integrated platform such as silicon photonics. RO acknowledges support from Generalitat Valenciana through the VALi+d postdoctoral program (exp APOSTD/2014/004). AM acknowledges funding from contracts TEC2014-51902-C2-1-R and TEC2014-61906-EXP (MINECO/FEDER, UE) and NANOMET PLUS-PROMETEOII/2014/034 (Conselleria d'Educacio, Cultura i Esport). Ortuño Molinero, R.; Cortijo-Munuera, M.; Martínez Abietar, AJ. (2017). Fano resonances and electromagnetically induced transparency in silicon waveguides loaded with plasmonic nanoresonators. Journal of Optics. 19(2):025003-1-025003-7. https://doi.org/10.1088/2040-8986/aa51e0 Schuller, J. A., Barnard, E. S., Cai, W., Jun, Y. C., White, J. S., & Brongersma, M. L. (2010). Plasmonics for extreme light concentration and manipulation. Nature Materials, 9(3), 193-204. doi:10.1038/nmat2630 Zijlstra, P., Paulo, P. M. R., & Orrit, M. (2012). Optical detection of single non-absorbing molecules using the surface plasmon resonance of a gold nanorod. Nature Nanotechnology, 7(6), 379-382. doi:10.1038/nnano.2012.51 Kauranen, M., & Zayats, A. V. (2012). Nonlinear plasmonics. Nature Photonics, 6(11), 737-748. doi:10.1038/nphoton.2012.244 Husnik, M., Niegemann, J., Busch, K., & Wegener, M. (2013). Quantitative spectroscopy on individual wire, slot, bow-tie, rectangular, and square-shaped optical antennas. Optics Letters, 38(22), 4597. doi:10.1364/ol.38.004597 Fan, P., Yu, Z., Fan, S., & Brongersma, M. L. (2014). Optical Fano resonance of an individual semiconductor nanostructure. Nature Materials, 13(5), 471-475. doi:10.1038/nmat3927 Rodríguez-Fortuño, F. J., Martínez-Marco, M., Tomás-Navarro, B., Ortuño, R., Martí, J., Martínez, A., & Rodríguez-Cantó, P. J. (2011).