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We study here the lateral evanescent coupling between photonic crystals cavities. The structure consists in two identical monomode Fabry–Perot nanocavities, integrated on silicon-on-insulator slot-waveguides (WG). Spectral and optical near field measurements were led and supported quantitatively by three dimensional simulations. It appears that this system produces a bimodal response: two resonances corresponding, respectively, to an even and odd mode. Particularly, the even case exhibits a field localization in the air slot inferior to λair/10. We demonstrate that merging a slotted WG structure with state-of-the-art nanocavities is a significant step toward an efficient air-slotted resonator. [ABSTRACT FROM AUTHOR]

The optical near field of a high-Q and ultrasmall volume photonic crystal nanocavity is visualized with a subwavelength resolution by using a scanning near-field optical microscope (SNOM) operating at the same time in collection-scanning mode and in interaction-scanning mode. It is shown that the nanocavity resonant mode is selectively visualized by using the SNOM interaction-scanning mode while the whole electromagnetic field surrounding the nanocavity is probed using the SNOM collection-scanning mode. The different optical near-field images are compared in light of a three-dimensional numerical analysis and we demonstrate an unexpected mode coupling at the cavity resonance. [ABSTRACT FROM AUTHOR]

Abstract: While optical near-field microscopy techniques have been devoted to mapping the electromagnetic fields down to the Raleigh limit, an exciting challenge is now to use near-field probes to manipulate in situ the properties of these electromagnetic fields. Here we report the resonance tuning and therefore switching of an ultra-low volume solid state resonator by evanescent interaction with a nanometric dielectric tip. By modelling the tip-nanocavity interaction, we demonstrate that a lossless interaction regime can be achieved in which the tip behaves as a pure optical path length modulator. To cite this article: B. Cluzel et al., C. R. Physique 9 (2008). [Copyright &y& Elsevier]