Fig. 1. (a) Structure of designed MG-1, a periodic metallic slit array (gray region) filled with two different kinds of media (colored blue regions) alternatively, forming a supercell containing two unit cells (i.e., m = 2). (b) Iso-frequency diagram indicating all possible diffraction orders. (c) and (d) are the magnetic field patterns for incident light with two different incident angles. The working wavelength is λ=650nm.

Fig. 2. (a) Structure of designed MG-2, a periodic metallic slit array (gray region) filled with two different kinds of media (colored blue regions) alternatively, forming a supercell containing two unit cells (i.e., m = 2). (b) Iso-frequency diagram indicating all possible diffraction orders. (c) is the magnetic field patterns for normally incident light.

Fig. 3. Structure of designed bi-layer MG system based on MG-1 and MG-2. (a) and (b) schematically show the scattering process for (a) positive incidence (PI) and (b) negative incidence (NI), respectively.

Fig. 4. (a) When the TM wave is incident to the bi-layer MGs, which are filled with impedance-matched material, the relationship curve between the transmission and reflection efficiency and the size of the air gap for PI and NI, respectively. Magnetic field diagram when the air gap with Δ=0 for (b) PI and (c) NI, and magnetic field diagram when the air gap with Δ=0.25λ for (d) PI and (e) NI.

Fig. 5. (a) Geometric structure of nonmagnetic unit cell for the design of magnetic MGs based on the local Fabry–Perot (FP) resonances. (b) Transmission and phase shift of the unit cell versus the height d of filled dielectric with ε_d=4 and μ_d=1. (c) and (d) show the schematic diagram of the redesigned bi-layer MGs for (c) PI and (d) NI, respectively.

Fig. 6. Performance demonstrations. (a) Relationship between the transmission/reflection efficiency and the size of the air gap for PI and NI. (b) Magnetic field pattern for PI when Δ=580nm. (c) Magnetic field pattern for NI when Δ=580nm.