Polarized spectral emittance from periodic micromachined surfaces: V. Undoped silicon: angular measurement in shallow lamellar gratings
- Department of Electrical Engineering, University of Pennsylvania, 200 S. 33rd St., Philadelphia, Pennsylvania 19104-6390 (United States)
Experimental results of thermal emittance from lamellar gratings in intrinsic silicon are presented along with a theoretical discussion. For azimuthal angular directions in shallow gratings, enhanced thermal emission plateaus and maxima are observed. In the case of [ital p]-polarized emission in the [Phi] = 90[degree] azimuth (parallel to the grating vector), the plateau arises when two diffractive orders can be supported; it lies between the Rayleigh polar angles corresponding to the forbidden zone. The experimentally observed angular dependence of the [ital s]-polarized emission for the [Phi] = 90[degree] azimuth has been compared with a coupled-wave calculation, and a respectable agreement has been obtained. For the experimentally observed s-polarized emission in the [Phi] = 0[degree] azimuth (perpendicular to the grating vector), there is an onset of enhanced emission at the polar angles that follows a simple empirical relation unrelated to any known diffraction law. By contrast, the [ital p]-polarized emission in the [Phi] = 0[degree] azimuth shows relatively little structure. These data illustrate the value of thermal emission for surveying multivariate absorption processes involving microstructures.
- DOE Contract Number:
- FG02-88ER13964
- OSTI ID:
- 6615206
- Journal Information:
- Applied Optics; (United States), Vol. 32:12; ISSN 0003-6935
- Country of Publication:
- United States
- Language:
- English
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