All-optical active plasmonic devices with memory and power-switching functionalities based on ε-near-zero nonlinear metamaterials

We theoretically propose and numerically investigate an active plasmonic device made up of a nonlinear epsilon-near-zero metamaterial slab of thickness smaller than 100 nm lying on a linear epsilon-near-zero metamaterial substrate. We predict that in free-space coupling configuration the system operating at low intensity displays plasmon mediated hysteresis behavior. The phase difference between the reflected and the incident optical waves turns out to be multivalued and dependent on the history of the excitation process. Such an hysteresis behavior allows the proposed system to be regarded as a memory device whose state is accessible by measuring either the mentioned phase difference or the power, which is multivalued as well, carried by the nonlinear plasmon wave. Since multiple plasmon powers comprise both positive and negative values, the device also operates as a switch of the plasmon power direction at each jump along an hysteresis loop.