Flexible Zero Refractive Index Optical Metamaterial with Matched Impedance

We demonstrate a flexible thin film zero refractive index optical metamaterial with matched impedance to free space and low absorption loss at 1.55 mu m. The metallo-dielectric multilayer structure with fishnet geometry was optimized by a genetic algorithm. The fabrication process and characterization approach are described. The experiment results agree well with the theoretical predictions, showing an effective index of n(eff) = 0.072 + 0.51i and an impedance of Z(eff)/Z(0) = 1.009 - 0.021i.