Highly directional thermal emitter
| DWPI Title: Highly directional thermal emitter device has two-dimensional periodic array provides directional thermal emission at peak wavelength between specific values when two-dimensional periodic array is heated |
| Abstract: A highly directional thermal emitter device comprises a two-dimensional periodic array of heavily doped semiconductor structures on a surface of a substrate. The array provides a highly directional thermal emission at a peak wavelength between 3 and 15 microns when the array is heated. For example, highly doped silicon (HDSi) with a plasma frequency in the mid-wave infrared was used to fabricate nearly perfect absorbing two-dimensional gratings structures that function as highly directional thermal radiators. The absorption and emission characteristics of the HDSi devices possessed a high degree of angular dependence for infrared absorption in the 10-12 micron range, while maintaining high reflectivity of solar radiation (˜64%) at large incidence angles. |
| Use: Highly directional thermal emitter. |
| Advantage: The light to the surface is strongly confined until energy is lost either via absorption in metal or radiation into free space. Thus the absorption and emission spectra is highly directional and narrow is bandwidth defined by symmetry and periodicity of surface structure for given wavelength. The rejection of solar spectrum is achieved effectively. |
| Novelty: The device has a two-dimensional periodic array (12) of heavily doped semiconductor structures on substrate (17). Two-dimensional periodic array is provided with characteristic sub-wavelength in orthogonal direction. Metal layer is between and in direct contact with heavily doped semiconductor structures for maximization of visible light reflectivity. Characteristic sub-wavelength periodicity is less than peak wavelength. Two-dimensional periodic array provides directional thermal emission at peak wavelength between specific values when two-dimensional periodic array is heated. |
| Filed: 9/16/2013 |
| Application Number: US14028181A |
| Tech ID: SD 12601.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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