Multiband and polarization-independent left-handed metamaterial with cross fractal structure

We present a polarization-independent fractal structure design for the construction of multiband terahertz (THz) left-handed metamaterial. The fractal structure consists of two layers of gold crosses array separated by gallium arsenide (GaAs) layer. The proposed cross fractal structure design originates from the fractal Sierpinski carpet. The electromagnetic properties of the metamaterial have been investigated by numerical simulation. Under the electromagnetic wave normal incidence the metamaterial exhibits negative refraction simultaneously around the frequencies of 0.18 THz, 0.30 THz and 0.71 THz. In contrast to the reported multiband metamaterials, the cross fractal metamaterial is independent of incident polarization, and the period in incident direction is extremely small as compared to the wavelength at the operational frequency. The proposed metamaterial with independent polarization and compact effect offers a way to develop multiband and miniaturization THz devices.