Geometry Induced Non-Linear Optical Properties of Elliptical Negative Index Metamaterials

We investigated the nonlinear response of an elliptical negative index metamaterial (eNIM) device using FTDT simulations. The device is a layered Ag-Si-Ag fishnet structure. Previous pump-probe experiments had shown that the device had the potential to serve as an all-optical picosecond switch. A visible pump pulse photoexcited silicon and quenched the transmission at around 1.6 μm. We used simulation to explore geometric optimizations to the switching ratio. We simulated the effects of reducing the anisotropy of the holes and found that improving the sidewall angle to 4° improved the switching ratio by 2 dB. Adding extra layers to the device did not appreciably change the switching ratio. Adding a second weakly coupled device increased the switching ratio by about 1 dB. We also investigated the effects of manufacturing improvements in the silver layer. Improving the scattering frequency γs of the Ag layer leads to a 2 dB improvement in switching ratio. If all of these manufacturing improvements can be realized, the device can provide picosecond switching of 3.3 dB for approximately 25 W of power.