Using self-resonant coils in a strongly coupled regime, we experimentally demonstrated efficient nonradiative power transfer over distances up to 8 times the radius of the coils. We were able to transfer 60 watts with approximately 40% efficiency over distances in excess of 2 meters. We present a quantitative model describing the power transfer, which matches the experimental results to within 5%. We discuss the practical applicability of this system and suggest directions for further study.

͑2007͔͒ are able to achieve efficient wireless power transfer from a source to a device separated by distances multiple times larger than the characteristic sizes of the resonators. This midrange approach is therefore suitable for remotely powering several devices from a single source. We explore the effect of adding multiple devices on the tuning and overall efficiency of the power transfer, and demonstrate this scheme experimentally for the case of coupling objects of different sizes: a large source ͑1 m 2 in area͒ powering two smaller devices ͑each Ӎ0.07 m 2 in area͒.

Articles you may be interested inThe role of group index engineering in series-connected photonic crystal microcavities for high density sensor microarrays Appl. Phys. Lett.Supercollimation is the propagation of light without diffraction using the properties of photonic crystals. We present the first experimental demonstration of supercollimation in a planar photonic crystal composed of nanoscale rods. Supercollimation was observed over distances of up to 1000 lattice periods.

We present numerical experiments showing how coupled-mode theory can be systematically applied to join very dissimilar photonic crystal waveguides with 100% transmission. Our approach relies on appropriately tuning the coupling of the evanescent tail of a cavity mode to each waveguide. The transition region between the waveguides may be as short as a few lattice spacings. Moreover, this technique only requires varying a small number of parameters (two for each waveguide in our example) and the tuning to each waveguide may be done separately, greatly simplifying the computations involved.

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