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The study of nanoantenna arrays has been a major research subject since the improvement of nanofabrication techniques allowed the design of subwavelength antennas, which proved to have new and interesting optical properties. Negative or near zero index behavior, extraordinary optical diffraction or transmission, huge field enhancement, the paths opened by these new optical devices are very diverse.
Our team specialises in the study of Infrared Metal-Insulator-Metal resonators, for which the most important applications are telecommunications and detection. In this work, we have specifically studied the effects of positional disorder on the optical behavior of such nanoresonator arrays. The general question we strive to answer is : how are the different loss channels (outgoing fields and absorption) modified between a periodic array and a disordered array?
Therefore, we use numerical simulations and caracterisation techniques to quantify precisely the difference in reflectance, diffraction and scattering when periodic arrays are disordered. We also take into account the different forms that disorder can have, whether it is a perturbation of a periodic array or an independent set of random positions.
So far, we have shown, both numerically and experimentally, that in the case of disordered nanoresonators, scattering is a very important loss channel. Indeed, the total scattered power in a disordered array is equivalent to the total diffracted power in a periodic array of the same resonators. Since resonator arrays can be optimised to have an extraordinary optical diffraction, i.e. a (possibly much) larger diffracted power than the specularly reflected power, our work shows that very highly scattering surfaces can be designed.
We are currently working on more complex arrays, especially with more than one type of resonator, in order to study the interplay of order, disorder, and coupling between resonators.
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