Fig. 1. (a) Schematic diagram of the right-angle triangular groove metal grating. Metal gratings at different scales: (b) superwavelength gratings, (c) near-wavelength gratings, and (d) subwavelength gratings.

Fig. 2. Absorption as a function of the period for Al TGGs with $\lambda =806.4\mathrm{nm}$, $\alpha =84\mathrm{deg}$, and $\theta =83.4\mathrm{deg}$: (a) global plot and (b) localized magnification.

Fig. 3. Electric field distributions of Al TGGs at periods of 19,780, 807, and 404 nm, respectively: (a–c) TE and (d–f) TM polarizations. Other parameters are $\alpha =84\mathrm{deg}$ and $\theta =83.4\mathrm{deg}$.

Fig. 4. Absorption as a function of blaze angle for Al TGGs at TM polarization for different scales. Other parameters are $\lambda =806.4\mathrm{nm}$ and $\theta =83.4\mathrm{deg}$.

Fig. 5. (a) Schematic structure of Al sinusoidal and rectangular gratings. (b) Equivalent diagrams of sinusoidal, rectangular, and triangular gratings. Absorption versus groove depth for (c) sinusoidal and (d) rectangular gratings with $d=404\mathrm{nm}$, $\lambda =806.4\mathrm{nm}$, and $\theta =83.4\mathrm{deg}$.

Fig. 6. Electric field distributions of Al sinusoidal gratings at TM polarization for $h_{\sin }$ of (a) 23.4 nm, (b) 424 nm, (c) 800 nm, and (d) 1172 nm, respectively. The electric field distributions of Al rectangular gratings at TM polarization for $h_{\mathrm{rect}}$ of (e) 18.7 nm, (f) 374 nm, (g) 752 nm, and (h) 1130 nm, respectively.