Negative refraction through an extraordinary transmission left-handed metamaterial slab

In this work we present numerical and experimental results of negative refraction through a negative index metamaterial based on miniaturized extraordinary transmission stacked subwavelength hole arrays, also known as stacked fishnet structures, working in the millimeter wave range. Analytical transmittance as a function of frequency and tangential momentum shows the conditions under which negative refraction is expected. Due to the role of the gap-surface-plasmon-polariton-like mode that gives rise to the resonant magnetic response of this structure, strong dispersion with the angle of incidence is expected. Experimental results using a quasioptical bench in the millimeter wave band demonstrate negative refraction and, besides, reasonable agreement with the simulation results is obtained. A discussion based on leaky waves serves to qualitatively explain the main features. The presented results may find application in the design of new lenses and devices both in the microwave, terahertz, and optical ranges.