Figure 1.

(a) Schematic of the MDM-MPAs. A plane wave is incident on the surface of the Au square array. The thicknesses of the Au squares, GaAs spacer, and Au mirror are 40, 40, and 80 nm, respectively. The whole structure is suspended in air. β is a cross-section through the structure along the x-z plane. (b) Illustration of absorber's rectangular lattice pattern, where the lattice constant in x direction is L_x = 400 nm and in y direction is L_y = 800 nm and the square dimension is d_x = d_y = 200 nm. (c) Demonstration of the wavevector (k), the vector normal to the surface (n), the two primitive lattice vectors (a or b) and the rotation angle φ in x–y plane, the components are marked in red.