“…As a new type of artificial materials, it can be applied to many disciplines, such as filter, waveguide, resonator and antenna [6][7][8][9]. To date, MMs have been demonstrated in every spectral range, from radio [10], microwave [4], mm-wave [11], THz [12], MIR [13], NIR [14], and even near optical [15]. Most of the MMs are made of periodically arranged metallic structures much smaller than the working wavelength in size.…”