Figure 1.

(a) Refractive indices (solid lines for the real part and dashed lines for the imaginary part) for AlN (red) and B₄C (blue). (b) Measured and (c) calculated absorptivity of the device at different illumination angles. Inset of (b) shows photograph of optical path in the FTIR setup. Inset of (c) displays schematic of superabsorber structure: the B₄C thin film (135 nm thick) is sputtered onto the AlN substrate.