Polarized spectral emittance from periodic micromachined surfaces. II. Doped silicon: Angular variation

The polarized directional spectral (3 μm≤λ≤14 μm) emittances (PDSE’s) of highly doped, micromachined, periodic structures on silicon were measured. These structures have dimensions that are comparable to the wavelengths of the measured radiation. Significant anisotropies and maxima were found for the s and p PDSE’s measured in emittance planes parallel and perpendicular to the grating-repeat vector. Wood’s singularities were clearly visible in the p PDSE on shallow gratings (depth ≤1.5 μm). Periodic maxima were observed in both the s and p PDSE in the emittance plane perpendicular to the grating vector due to standing-wave modes in the slots of the grating. It is concluded that the PDSE provides detailed information on the characteristics of the electromagnetic modes associated with surface microstructures.