(a) Schematic diagram showing TM polarized light incident at an angle θ_inc on a unit cell of the proposed selective absorber structure which consists of a graded index slab having thickness L_y  = 2.67 μm, with nine columns and nineteen rows of metallic nanorods embedded in it. The three rod columns at left are made out of TiN and have a rod radius of 24 nm. The three middle ones are made out of rhodium and have a rod radius of 14 nm. The three rod columns at right are made out of TiN and have a rod radius of 8 nm. The horizontal interparticle spacing is a_x  = 800 nm, and the vertical one is a_y  = 130 nm. Consecutive columns of the same metal type are vertically shifted by a_y/3 to ensure that the rods sense a smooth variation in the slab's refractive index. (b) Numerically calculated R, T, and A spectra for the structure shown in (a) in the case of normally incident (θ_inc = 0) TM polarized light. (c–e) Two-dimensional (2D) color contour plots for R, T, and A, in terms of frequency and θ_inc, for TM light incident on the structure shown in (a).