Coherent spontaneous emission of light by thermal sources
Résumé
The emission of light by a material at temperature T has been shown recently to be coherent in the near field. Theses propertis were attributed to the thermal excitation of surface polaritons. We review the origin of this phenomenon. We analyze the influrence of the microstructure and temperature on the coherence properties and show how to engineer thermoradiative properties of surfaces. We report the design of a quasi-isotropic source and a very directional source of thermal light. We also report a measurement of the transverse coherence lenght of a thermal source of light.