Based on the analysis of absorptances of plane-parallel objects, distinctive features of their thermal radiation caused by multi-beam interference are investigated. Using a semiconductor as an example, thermal radiation spectra for plane-parallel and identical non-plane-parallel plates in the spectral region beyond the fundamental absorption edge are calculated, and a comparison of the parameters of these spectra was carried out. It is shown that, in spectral regions corresponding to interference maxima, the radiant emittance of a plane-parallel plate can exceed many times over that of non-plane-parallel plate. For very small values of the absorption coefficient of a plane-parallel plate, its radiant emittance can attain the value of 0.5 of that of a blackbody in these spectral regions. It is proved that the results obtained can be used for creation of new controllable thermal radiation sources.
Results of investigations of the multifunctional emitting element based on a p<sup>+</sup>-p-p<sup>+</sup> Ge structure with anisotropic conductivity induced by magnetic field are presented. It was shown that the presence of complex controlled concentration profiles in the element essentially widens functional possibilities of the emitting element, which enables to model positive, negative or alternating contrast. This provides possibility to use it as a base in the specialized emitting sources intended for the calibration of infrared systems.
The influence of a magnetic field on the polarization characteristics of thermal radiation emitted by isotropic semiconductors was investigated theoretically. It was shown that thermal emission is polarized and the degree of polarization depends on the applied magnetic field and experiment geometry. Muller matrix formalism was used firstly for the decision of such problems.