Epsilon near zero metamaterials for ultra-low power nonlinear applications

Epsilon-near-zero metamaterial samples, composed of five alternating bi-layers of silica and silver, are fabricated using the electron-beam evaporator. Nonlinear properties of samples are measured using a pulsed Ti:sapphire laser by the z-scan technique. It is observed that the real part of the nonlinear Kerr index is one order of magnitude higher than the values expected from a naive averaging of the corresponding coefficients of metal and dielectric layers (the correct averaging should be performed with respect to the nonlinear susceptibility), so that its value is actually of the same order of magnitude as that of a single silver layer. At the same time, the transmission of our samples is remarkably higher than that of a single silver layer of the same thickness. These characteristics have a great impact on the amount of optical energy which can be pumped into the structure, thus allowing its nonlinear properties to be accumulated over long propagation distance along the sample. This property is very promising for applications, which are based on the modulation of phase, amplitude or frequency of light, especially those which require low-power operations, such as all-optical switching and memory elements.