Bridging the gap in nanoantennas(th a modified version of the scattering-...)

Date:4/19/2009

th a modified version of the scattering-type near-field microscope that the Max Planck and nanoGUNE researchers had pioneered over the last decade. For this work, they chose dielectric tips and operated in transmission mode, allowing for imaging local antenna fields in details as small as 50 nm without disturbing the antenna. "By monitoring the near-field oscillations of the different antennas with our novel near-field microscope, we were able to directly visualize how matter inside the gap affects the antenna response. The effect could find interesting applications for tuning of optical antennas" says Rainer Hillenbrand leader of the Nanooptics group at the newly established research institute CIC nanoGUNE Consolider.

The nanooptics group from DIPC and CSIC-UPV/EHU led by Javier Aizpurua in San Sebastin fully confirmed and helped to understand the experimental results by means of full electrodynamic calculations. The calculated maps of the antenna fields are in good agreement with the experimentally observed images. The simulations add deep insights into the dependence of the antenna modes on the bridging, thus confirming the validity and robustness of the "loading" concept to manipulate and control nanoscale local fields in optics.

Furthermore, the researchers applied the well developed radiofrequency antenna design concepts to visible and infrared frequencies, and explained the behavior of the loaded antennas within the framework of optical circuit theory. A simple circuit model showed remarkable agreement with the results of the numerical calculations of the optical resonances. "By extending circuit theory to visible and infrared frequencies, the design of novel photonic devices and detectors will become more efficient. This bridges the gap between these two disciplines" says Javier Aizpurua.

With this work, the researches provide first experimental evidence that the local antenna fields can be controlled by gap-loading. This opens the door for
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Contact: Oihane Lakar oihane@elhuyar.com 34-943-363-040 Elhuyar Fundazioa Source:Eurekalert

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