Jacob Khurgin, Johns Hopkins University
Nanoplasmonic Metamaterials: Figures of Merit
Johns Hopkins University
A simple analytical theory of plasmonic enhancement of optical nonlinearities in various nanoplasmonic structures is developed. It is shown that in simple structures roughly two-to-three order enhancement of effective third order nonlinear susceptibility can be obtain, while in more complicated arrangements of plasmonic dimers and nanoantennae, enhancement can be as high as four-to-five orders of magnitude. At the same time, if one introduces a more practical figure of merit for nonlinearity, as a maximum attainable phase shift per 10dB loss, this phase shift can never exceed a few degrees, thus making photonic switching in metamaterials all but unattainable. This self-contradictory behavior is caused by a combination of inherently low values of nonlinear susceptibility and large loss in the metal. The conclusion is then that nanoplasmonic metamaterials may enhance weak nonlinearities for various sensing applications, but are rather ineffectual in photonic switching and modulation.